Android开发学习之路--网络编程之xml、json

    一般网络数据通过http来get，post，那么其中的数据不可能杂乱无章，比如我要post一段数据，肯定是要有一定的格式，协议的。常用的就是xml和json了。在此先要搭建个简单的服务器吧，首先呢下载xampp，然后安装之类的就不再多讲了，参考http://cnbin.github.io/blog/2015/06/05/mac-an-zhuang-he-shi-yong-xampp/。安装好后，启动xampp，之后在浏览器输入localhost或者127.0.0.1就可以看到如下所示了：

    这个就表示服务器已经运行了，具体的代码都是放在这个/Applications/XAMPP/htdocs目录下的。然后待会儿编写个xml文件也放在这里。 编写个简单的xml文件吧。

<Person>

  2  <Teacher>

  3     <name>xiao hong</name>

  4    <age>25</age>

  5    <sex>woman</sex>

  6    <class>english</class>

  7  </Teacher>

  8  <Student>

  9     <name>xiao ming</name>

 10    <age>15</age>

 11    <sex>man</sex>

 12  </Student>

 13 </Person>

 14 

    这里为了方便，我在htdocs下面新建了一个test文件夹，然后再新建了一个person.xml文件，习惯了用vim，这里就用vim来实现了一把，保存退出后，我们去看下效果，打开chrome浏览器，输入http://localhost/test/person.xml。发现浏览器如下图所示：

    显示的内容就是我们文件的内容，接下去通过app去获取这个信息。

    xml解析主要有三种方式，SAX，Pull，Dom。下面就用这几种方法来实现下。

    首先是SAX方式，SAX方式主要是两部分组成，一部分是解析器，也就是XMLReader接口，负责读取XML文档，另一部分是事件处理器ContentHandler，负责对发送事件响应和进行XML文档处理。

    继承DefaultHandler，并重写5个父类的方法。

    1、startDocument方法：开始XML解析的时候调用。

    2、startElement方法：开始解析某个节点的时候调用。

    3、characters方法：获取节点内容的时候调用。

    4、endElement方法：解析完某个节点的时候调用。

    5、endDocument方法：完成XML解析时候调用。

    先新建类SAXContentHandler类，继承DefaultHandler类，编写代码如下：

package com.jared.emxmlstudy;

import android.util.Log;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * Created by jared on 16/2/19.
 */
public class SAXContentHandler extends DefaultHandler {

    private static final String TAB = "SAXContentHandler";

    private String nodeName;
    private StringBuffer mName;
    private StringBuffer mAge;
    private StringBuffer mSex;
    private StringBuffer mClass;

    @Override
    public void startDocument() throws SAXException {
        mName = new StringBuffer();
        mAge = new StringBuffer();
        mSex = new StringBuffer();
        mClass = new StringBuffer();
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        nodeName = localName;
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        if("name".equals(nodeName)) {
            mName.append(ch, start, length);
        }else if("age".equals(nodeName)) {
            mAge.append(ch, start, length);
        } else if("sex".equals(nodeName)) {
            mSex.append(ch, start, length);
        } else if("class".equals(nodeName)) {
            mClass.append(ch, start, length);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if("Teacher".equals(localName)) {
            Log.d(TAB, "This is Teacher");
            Log.d(TAB, "name is:" + mName.toString().trim());
            Log.d(TAB, "age is:" + mAge.toString().trim());
            Log.d(TAB, "sex is:" + mSex.toString().trim());
            Log.d(TAB, "class is:" + mClass.toString().trim());
            mName.setLength(0);
            mAge.setLength(0);
            mSex.setLength(0);
            mClass.setLength(0);
        } else if("Student".equals(localName)) {
            Log.d(TAB, "This is Student");
            Log.d(TAB, "name is:" + mName.toString().trim());
            Log.d(TAB, "age is:" + mAge.toString().trim());
            Log.d(TAB, "sex is:" + mSex.toString().trim());
            mName.setLength(0);
            mAge.setLength(0);
            mSex.setLength(0);
        }
    }

    @Override
    public void endDocument() throws SAXException {

    }
}

    这里要使用三种方法，所以修改布局如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_margin="10dp"
    tools:context="com.jared.emxmlstudy.MainActivity">

    <Button
        android:id="@+id/getXmlsax"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="SAX方式获取"/>

    <Button
        android:id="@+id/getXmlpull"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Pull方式获取"/>

    <Button
        android:id="@+id/getXmldom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Dom方式获取"/>

</LinearLayout>

   然后MainActivity中添加代码如下；

package com.jared.emxmlstudy;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;

import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;

import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;

import java.io.StringReader;

import javax.xml.parsers.SAXParserFactory;

import cz.msebera.android.httpclient.Header;

public class MainActivity extends AppCompatActivity {

    private static final String xmlUrl = "http://192.168.1.102/test/person.xml";

    private Button mGetXmlSax;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mGetXmlSax = (Button)findViewById(R.id.getXmlsax);
        mGetXmlSax.setOnClickListener(new myOnClickListener());

    }

    private class myOnClickListener implements View.OnClickListener {
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.getXmlsax:
                    sendRequestWithAsyncHttpClient(xmlUrl);
                    break;
                default:
                    break;
            }
        }
    }

    private void sendRequestWithAsyncHttpClient(String url) {

        AsyncHttpClient client = new AsyncHttpClient();
        client.get(url, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(int i, Header[] headers, byte[] bytes) {
                try {
                    String response = new String(bytes, 0, bytes.length, "utf-8");
                    parseXMLWithSax(response);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {

            }
        });
    }

    private void parseXMLWithSax(String xmlData) {
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            XMLReader xmlReader = factory.newSAXParser().getXMLReader();
            SAXContentHandler mHandler = new SAXContentHandler();
            xmlReader.setContentHandler(mHandler);
            xmlReader.parse(new InputSource(new StringReader(xmlData)));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

    这里用到了AsyncHttpClient，具体库的添加参考上一篇文章Android开发学习之路--网络编程之初体验。好了，这里在发送请求的时候，成功再调用parseXMLWithSax进行解析。这里的地址是192.168.1.102，因为是真机调试，连接到了同一个网段，然后手机就可以访问我们的服务器了。

    实例化一个factory，通过XMLReader来读取解析。运行点击按钮如下显示：

02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: This is Teacher
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: name is:xiao hong
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: age is:25
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: sex is:woman
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: class is:english
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: This is Student
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: name is:xiao ming
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: age is:15
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: sex is:man

    可以发现已经得到我们想要的信息了。

    接着使用Pull方式，开始解析可以通过调用它的next方法，获取下一个事件，可以通过getAttribute方法获取属性，通过nextText方法来获取节点的值。编写代码如下：

package com.jared.emxmlstudy;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;

import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserFactory;

import java.io.StringReader;

import javax.xml.parsers.SAXParserFactory;

import cz.msebera.android.httpclient.Header;

public class MainActivity extends AppCompatActivity {

    private static final String TAB = "XMLParse";
    private static final String xmlUrl = "http://192.168.1.102/test/person.xml";

    private Button mGetXmlSax;
    private Button mGetXmlPull;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mGetXmlSax = (Button)findViewById(R.id.getXmlsax);
        mGetXmlPull = (Button)findViewById(R.id.getXmlpull);

        mGetXmlSax.setOnClickListener(new myOnClickListener());
        mGetXmlPull.setOnClickListener(new myOnClickListener());

    }

    private class myOnClickListener implements View.OnClickListener {
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.getXmlsax:
                    sendRequestWithSax(xmlUrl);
                    break;
                case R.id.getXmlpull:
                    sendRequestWithPull(xmlUrl);
                    break;
                default:
                    break;
            }
        }
    }

    private void sendRequestWithPull(String url) {
        AsyncHttpClient client = new AsyncHttpClient();
        client.get(url, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(int i, Header[] headers, byte[] bytes) {
                try {
                    String response = new String(bytes, 0, bytes.length, "utf-8");
                    parseXMLWithPull(response);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {

            }
        });
    }

    private void parseXMLWithPull(String xmlData) {
        try {
            XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
            XmlPullParser xmlPullParser = factory.newPullParser();
            xmlPullParser.setInput(new StringReader(xmlData));
            int eventType = xmlPullParser.getEventType();
            String mName = "";
            String mAge = "";
            String mSex = "";
            String mClass = "";

            while (eventType != XmlPullParser.END_DOCUMENT) {
                String  nodeName = xmlPullParser.getName();
                switch (eventType) {
                    case XmlPullParser.START_TAG: {
                        if("name".equals(nodeName)) {
                            mName = xmlPullParser.nextText();
                        } else if("age".equals(nodeName)) {
                            mAge = xmlPullParser.nextText();
                        } else if("sex".equals(nodeName)) {
                            mSex = xmlPullParser.nextText();
                        } else if("class".equals(nodeName)) {
                            mClass = xmlPullParser.nextText();
                        }
                        break;
                    }
                    case XmlPullParser.END_TAG: {
                        if("Teacher".equals(nodeName)) {
                            Log.d(TAB, "This is Teacher");
                            Log.d(TAB, "name is:" + mName.trim());
                            Log.d(TAB, "age is:" + mAge.trim());
                            Log.d(TAB, "sex is:" + mSex.trim());
                            Log.d(TAB, "class is:" + mClass.trim());
                        } else if("Student".equals(nodeName)) {
                            Log.d(TAB, "This is Student");
                            Log.d(TAB, "name is:" + mName.trim());
                            Log.d(TAB, "age is:" + mAge.trim());
                            Log.d(TAB, "sex is:" + mSex.trim());
                        }
                    }
                    default:
                        break;
                }
                eventType = xmlPullParser.next();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void sendRequestWithSax(String url) {

        AsyncHttpClient client = new AsyncHttpClient();
        client.get(url, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(int i, Header[] headers, byte[] bytes) {
                try {
                    String response = new String(bytes, 0, bytes.length, "utf-8");
                    parseXMLWithSax(response);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {

            }
        });
    }

    private void parseXMLWithSax(String xmlData) {
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            XMLReader xmlReader = factory.newSAXParser().getXMLReader();
            SAXContentHandler mHandler = new SAXContentHandler();
            xmlReader.setContentHandler(mHandler);
            xmlReader.parse(new InputSource(new StringReader(xmlData)));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

    运行结果如下：

02-19 21:52:01.391 19388-19388/? D/XMLParse: This is Teacher
02-19 21:52:01.391 19388-19388/? D/XMLParse: name is:xiao hong
02-19 21:52:01.391 19388-19388/? D/XMLParse: age is:25
02-19 21:52:01.391 19388-19388/? D/XMLParse: sex is:woman
02-19 21:52:01.391 19388-19388/? D/XMLParse: class is:english
02-19 21:52:01.391 19388-19388/? D/XMLParse: This is Student
02-19 21:52:01.391 19388-19388/? D/XMLParse: name is:xiao ming
02-19 21:52:01.391 19388-19388/? D/XMLParse: age is:15
02-19 21:52:01.391 19388-19388/? D/XMLParse: sex is:man

    最后一种是Dom方式，Dom方式主要比较耗费内存，需要遍历所有，一般手机上的app开发不太适用。那就简单实现下吧，还是利用Async-HttpClient，接着编写代码如下：

    private void parseXMLWithDom(String xmlData) {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        String mName = "";
        String mAge = "";
        String mSex = "";
        String mClass = "";
        try {
            DocumentBuilder builder = factory.newDocumentBuilder();
            //Document document = builder.parse(xmlData);
            Document document = builder.parse(new InputSource(new StringReader(xmlData)));
            Element root = document.getDocumentElement();
            Log.d(TAB, "根节点名称：" + root.getTagName());
            NodeList items = root.getElementsByTagName("Teacher");

            Element personElement = (Element)items.item(0);
            Log.d(TAB, "根节点名称：" + personElement.getTagName());
            NodeList childNodes = personElement.getChildNodes();
            Log.d(TAB, "This is Teacher");
            for(int i = 0; i < childNodes.getLength(); i++) {
                Node grandElement = childNodes.item(i);
                if(grandElement.getNodeType() == Node.ELEMENT_NODE) {
                    if("name".equals(grandElement.getNodeName())) {
                        mName = grandElement.getFirstChild().getNodeValue();
                        Log.d(TAB, "name is:" + mName.trim());
                    } else if("age".equals(grandElement.getNodeName())) {
                        mAge = grandElement.getFirstChild().getNodeValue();
                        Log.d(TAB, "age is:" + mAge.trim());
                    } else if("sex".equals(grandElement.getNodeName())) {
                        mSex = grandElement.getFirstChild().getNodeValue();
                        Log.d(TAB, "sex is:" + mSex.trim());
                    } else if("class".equals(grandElement.getNodeName())) {
                        mClass = grandElement.getFirstChild().getNodeValue();
                        Log.d(TAB, "class is:" + mClass.trim());
                    }
                }
            }
        } catch (Exception e){
            e.printStackTrace();
        }
    }

    这里简单的就实现了Teacher的，student的就没有添加，相信也是很容易的了，其余的代码和上述类似，运行效果如下：

02-20 09:16:49.601 1353-1353/? D/XMLParse: 根节点名称：Person
02-20 09:16:49.601 1353-1353/? D/XMLParse: 根节点名称：Teacher
02-20 09:16:49.601 1353-1353/? D/XMLParse: This is Teacher:9
02-20 09:16:49.601 1353-1353/? D/XMLParse: name is:xiao hong
02-20 09:16:49.601 1353-1353/? D/XMLParse: age is:25
02-20 09:16:49.601 1353-1353/? D/XMLParse: sex is:woman
02-20 09:16:49.601 1353-1353/? D/XMLParse: class is:english

    关于xml基本上先学习这些知识了。接着学习json的知识。

    首先和xml一样，新建一个person.json文件，如下：

  1 [{"name":"xiao hong", "age":"25", "sex":"wonan"},

  2  {"name":"xiao ming", "age":"15", "sex":"man"},

  3  {"name":"xiao qiang", "age": 30, "sex":"man"}]

    保存到和xml同一级目录下，运行浏览器如下图所示：

    如图可知配置已经ok了，那么接下来就开始完成代码了，这里要使用JSONObject和GSON来实现，布局如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_margin="10dp"
    tools:context="com.jared.emjsonstudy.MainActivity">

    <Button
        android:id="@+id/getJSONObject"
        android:text="Get Json With JSONObject"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"/>

    <Button
        android:id="@+id/getGSON"
        android:text="Get Json With GSON"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"/>

</LinearLayout>

    接着实现代码，还是用了Async-HttpClient来实现，代码如下：

package com.jared.emjsonstudy;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;

import org.json.JSONArray;
import org.json.JSONObject;

import cz.msebera.android.httpclient.Header;

public class MainActivity extends AppCompatActivity {

    private static final String TAB = "JSONStudy";
    private static final String JSON_URL = "http://192.168.1.102/test/person.json";
    private Button mGetJSONObjectBtn;
    private Button mGetGSONBtn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mGetJSONObjectBtn = (Button)findViewById(R.id.getJSONObject);
        mGetGSONBtn = (Button)findViewById(R.id.getGSON);

        mGetJSONObjectBtn.setOnClickListener(new myOnClickListener());
        mGetGSONBtn.setOnClickListener(new myOnClickListener());
    }

    private class myOnClickListener implements View.OnClickListener {
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.getJSONObject:
                    getJSONWithJSONObject(JSON_URL);
                    break;
                case R.id.getGSON:
                    break;
                default:
                    break;
            }
        }
    }

    private void parseJSONWithJSONObject(String jsonData) {
        try {
            JSONArray jsonArray = new JSONArray(jsonData);
            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                String mName = jsonObject.getString("name");
                String mAge = jsonObject.getString("age");
                String mSex = jsonObject.getString("sex");

                Log.d(TAB, "name is: " + mName);
                Log.d(TAB, "age is: " + mAge);
                Log.d(TAB, "sex is:" + mSex);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void getJSONWithJSONObject(String url) {
        AsyncHttpClient client = new AsyncHttpClient();
        client.get(url, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(int i, Header[] headers, byte[] bytes) {
                try {
                    String response = new String(bytes, 0, bytes.length, "utf-8");
                    parseJSONWithJSONObject(response);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {

            }
        });
    }
}

    如上代码明显比xml的简单多了，JSONArray获取到Json数据，然后通过JSONObject来获取对应键值的内容。因为我的电脑ip地址是192.168.1.102，手机和电脑在同一个网段，所以直接利用真机来测试，效果如下：

02-20 10:13:20.521 4947-4947/? D/JSONStudy: name is: xiao hong
02-20 10:13:20.521 4947-4947/? D/JSONStudy: age is: 25
02-20 10:13:20.521 4947-4947/? D/JSONStudy: sex is:wonan
02-20 10:13:20.521 4947-4947/? D/JSONStudy: name is: xiao ming
02-20 10:13:20.521 4947-4947/? D/JSONStudy: age is: 15
02-20 10:13:20.521 4947-4947/? D/JSONStudy: sex is:man
02-20 10:13:20.521 4947-4947/? D/JSONStudy: name is: xiao qiang
02-20 10:13:20.521 4947-4947/? D/JSONStudy: age is: 30
02-20 10:13:20.521 4947-4947/? D/JSONStudy: sex is:man

   

    接着使用google的开源库GSON来实现，用到开源库，那就先下载了。gson下载地址：GSON下载地址点击这里。gson gitbub地址：https://github.com/google/gson。
    GSON库主要是将一段JSON格式的字符串自动映射成一个对象，从而不需要编写代码去解析。这里新建一个Person类来获取数据，代码如下：

package com.jared.emjsonstudy;

/**
 * Created by jared on 16/2/20.
 */
public class Person {
    private String name;
    private String age;
    private String sex;

    public String getName() {
        return name;
    }

    public String getAge() {
        return age;
    }

    public String getSex() {
        return sex;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }
}

    MainActivity中添加代码：

  void parseJSONWithGSON(String jsonData) {
        Gson gson = new Gson();
        List<Person> personList = gson.fromJson(jsonData,
                new TypeToken<List<Person>>(){}.getType());
        for (Person person :personList) {
            Log.d(TAB, "Gson: name is: " + person.getName());
            Log.d(TAB, "Gson: age is: " + person.getAge());
            Log.d(TAB, "Gson: sex is:" + person.getSex());
        }
    }

    void getJSONWithGSON(String url) {
        AsyncHttpClient client = new AsyncHttpClient();
        client.get(url, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(int i, Header[] headers, byte[] bytes) {
                try {
                    String response = new String(bytes, 0, bytes.length, "utf-8");
                    parseJSONWithGSON(response);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {

            }
        });
    }

    这里new了一个Gson，然后通过fromJson的方法，通过TypeToken获取数据并保存到Person列表中。运行看下效果：

02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: name is: xiao hong
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: age is: 25
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: sex is:wonan
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: name is: xiao ming
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: age is: 15
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: sex is:man
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: name is: xiao qiang
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: age is: 30
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: sex is:man

    当然如果想要生存json数据，也是可以用gson的tojson方法的。