读取网址中json数据 转换为java格式

http://yu-duo.iteye.com/blog/1684846

 

内容描述： 
条件：http://www.aaa/Bbb/ccclist.json 
将条件中的json数据转换为javalist形式； 

思路（脉络）： 
1. 读取json字符串； 
2. 分析字符串格式； 
3. 取出我需要的字符串（按照我需要的格式取出字符串）； 
4. 查看字符串编码格式是否正确 
5. 使用json类库转换为beanlist形式； 
6.      bean中属性格式要和字符串中的对应； 

继续想： 
1.读取网址中的json数据需要使用httpclient/httpUrLconnettion读取网址内容； 
2.字符串格式如下：{"stutus":2,"result":[{"company_name":"a公司","company_id":"-1"}, {"company_name":"222","company_id":"-55"},{"company_name":"撒旦法接 口"company_id":"-33"},{"company_name":"多的"company_id":"-34"}]} 

分析格式：此字符串可以看做map的嵌套， 
Map 
Map<”status”,”2”> 
Map <”result”,”list”> 
    Map<”company_name”,company.get(company_id)> 
    Map<”company_id”,company.get(company_name)> 
3.取出需要的数据 
我需要的数据位result中的list，所以用截取字符串方法将其取出来，这里用到了从0学java总截取字符串数据的的内容substring、indexof这两个知识点。 
4.查看字符串格式是否正确 
常用编码格式为utf-8，坚持文件属性的编码格式，将其更改为utf-8，或者在读取时用getmethod设置utf-8。 
5.使用json类库转换为beanlist形式 
首先声明一个objectmapper对象，使用其中的TypeReference方法将我们处理好的数据自动解析为bean形式，存放用该bean类型的list中。 
最后遍历输出list中存放内容即可。 

声明：此处读取数据来源为iteye一篇博客，使用了其代码，虽然方法很老，但是解决问题了，要把这个问题涉及的知识点好好看一下梳理一下。 


全部实现代码如下： 

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.params.HttpClientParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;

public class ReadingWebContent {
    /**
     *
     * @param url
     * @return
     * @throws Exception
     */
    public static String getContent(String url) throws Exception{
        String CONTENT_CHARSET = "UTF-8";
        String backContent = null;
//        private static final END_OBJECT = "0";
        String eND_OBJECT = "0";

        HttpClient httpclient = null;
        HttpGet httpget = null;
        try {

            HttpParams params = new BasicHttpParams();

            HttpConnectionParams.setConnectionTimeout(params, 180 * 1000);
            HttpConnectionParams.setSoTimeout(params, 180 * 1000);
            HttpConnectionParams.setSocketBufferSize(params, 8192);

            HttpClientParams.setRedirecting(params, false);

            httpclient = new DefaultHttpClient(params);

            httpget = new HttpGet(url);                 httpclient.getParams().setParameter(HttpMethodParams.HTTP_CONTENT_CHARSET, CONTENT_CHARSET);
            HttpResponse response = httpclient.execute(httpget);

            HttpEntity entity = response.getEntity();
            if (entity != null) {

                InputStream is = entity.getContent();
                BufferedReader in = new BufferedReader(new InputStreamReader(is));
                StringBuffer buffer = new StringBuffer();
                String line = "";
                while ((line = in.readLine()) != null) {
                    buffer.append(line);
                }

                backContent = buffer.toString();
            }
        } catch (Exception e) {
            httpget.abort();
            backContent = "���쳣,��ȡ����";
            System.out.println("-------------�쳣��ʼ");
            e.printStackTrace();
            System.out.println("-------------�쳣����");
        }finally{

            if(httpclient != null)
                httpclient.getConnectionManager().shutdown();
        }
        return backContent;
    }

    @SuppressWarnings("static-access")
    public static void main(String[] args) throws Exception{
        ReadingWebContent a = new ReadingWebContent();
        String address = a.getContent("http://www.aaa/Bbb/ccclist.json

        String data = address.substring(address.indexOf("result") + 8, address.length() -1 );
        ObjectMapper mapper = new ObjectMapper();
        List<Company> list = mapper.readValue(data, new TypeReference<List<Company>>(){});

        for (int i = 0; i < list.size(); i++) {

            System.out.println(list.get(i).getCompany_id());
            System.out.println(list.get(i).getCompany_name());
        }
        System.out.println(list.size());

    }
}