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  • FastJSON 简介及其Map/JSON/String 互转

    转载http://blog.csdn.net/hongwangzhang/article/details/51260879

    在日志解析，前后端数据传输交互中，经常会遇到 String 与 map、json、xml 等格式相互转换与解析的场景，其中 json 基本成为了跨语言、跨前后端的事实上的标准数据交互格式。应该来说各个语言中 解析 json 的库都一大片（具体 json 格式与三方库的介绍请见： http://www.json.org/json-zh.html ），比如 Python 都集成在了内置库中，成为标准 API，今天我们要聊的是 Java 中如何方便的使用 json 格式。

    从上面的链接介绍中我们可以看到，java 的三方 json 库是最多的，可谓百花齐放百家争鸣的节奏。。。但是，某些库存在链式依赖的问题，使用的时候要注意，如果你没用 maven 管你你的依赖，用起来会很痛苦，比如 json-lib、smart-json 等。下面我要推荐的是阿里巴巴工程师开源的一个 json 库：FastJSON，这个库在解析速度和易用性上来说都很不错。  

    1、了解fastjson

    1.1 Fastjson介绍

    Fastjson是一个Java语言编写的JSON处理器。 
    1、遵循 http://json.org 标准，为其官方网站收录的参考实现之一。 
    2、功能qiang打，支持JDK的各种类型，包括基本的JavaBean、Collection、Map、Date、Enum、泛型。 
    3、无依赖，不需要例外额外的jar，能够直接跑在JDK上。 
    4、开源，使用Apache License 2.0协议开源。

    1.2 如果获得Fastjson？ 
    https://github.com/alibaba/fastjson

    2、主要的使 用入口

    Fastjson API入口类是com.alibaba.fastjson.JSON，常用的序列化操作都可以在JSON类上的静态方法直接完成。

    public static final Object parse(String text); // 把JSON文本parse为JSONObject或者JSONArray 
public static final JSONObject parseObject(String text)； // 把JSON文本parse成JSONObject    
public static final <T> T parseObject(String text, Class<T> clazz); // 把JSON文本parse为JavaBean 
public static final JSONArray parseArray(String text); // 把JSON文本parse成JSONArray 
public static final <T> List<T> parseArray(String text, Class<T> clazz); //把JSON文本parse成JavaBean集合 
public static final String toJSONString(Object object); // 将JavaBean序列化为JSON文本 
public static final String toJSONString(Object object, boolean prettyFormat); // 将JavaBean序列化为带格式的JSON文本 
public static final Object toJSON(Object javaObject); 将JavaBean转换为JSONObject或者JSONArray。

    3、有关类库的一些说明

    SerializeWriter：相当于StringBuffer

    JSONArray：相当于List<Object>

    JSONObject：相当于Map<String, Object>

    JSON反序列化没有真正数组，本质类型都是List<Object>

    4、fastjson还有很多很高级的特性

    比如支持注解、支持全类型序列化，这些都是很好的特性，功能强大，不在本次测试范围。

    5、测试代码

    package lavasoft.stu.json; 

    import com.alibaba.fastjson.JSON;
    
import com.alibaba.fastjson.serializer.SerializeConfig;
    
import com.alibaba.fastjson.serializer.SimpleDateFormatSerializer;
    

    import java.util.*;
    

    /**
    

      

    • Created by IntelliJ IDEA.
      • 

    • 

    • @author leizhimin 11-11-22 上午9:15
      
*/
      
public class Foo {
      
  private String vString = "vStringhehhehe";
      
  private char vchar = 'x';
      • 

    

      private byte vbyte = 64;
    
  private short vshort = 128;
    
  private int vint = 65535;
    
  private long vlong = 9999999L;
    

      private float vfloat = 12.1f;
    
  private double vdouble = 22.203d;
    

      private boolean vboolean = false;
    

    //	private Date vdate = new Date();
    
  private Date dddd = new Date();
    
  private Date vDate = new Date();
    
  private Date v_Date = new Date();
    
  private Object vnull = null;
    

      private String[] avString = {"aaa", "bbb", "ccc"};
    
  private int[] avint = {1, 2, 3, 4};
    
  private boolean[] avboolean = {true, false, true, true};
    

      private List<String> listString = new ArrayList<String>();
    
  private Map<String, String> map = new HashMap<String, String>();
    

      private Bar bar = new Bar();
    
  private Bar[] avBar = {new Bar(), new Bar()};
    
  private List<Bar> listBar = new ArrayList<Bar>();
    

      {
    
    listString.add("listString1");
    
    listString.add("listString2");
    
    listString.add("listString3");
    

        map.put("x", "s11111x");
    
    map.put("y", "s22222y");
    
    map.put("z", "s33333z");
    

        listBar.add(new Bar());
    
    listBar.add(new Bar());
    
    listBar.add(new Bar());
    
  }
    

      public String getvString() {
    
    return vString;
    
  }
    

      public void setvString(String vString) {
    
    this.vString = vString;
    
  }
    

      public char getVchar() {
    
    return vchar;
    
  }
    

      public void setVchar(char vchar) {
    
    this.vchar = vchar;
    
  }
    

      public byte getVbyte() {
    
    return vbyte;
    
  }
    

      public void setVbyte(byte vbyte) {
    
    this.vbyte = vbyte;
    
  }
    

      public short getVshort() {
    
    return vshort;
    
  }
    

      public void setVshort(short vshort) {
    
    this.vshort = vshort;
    
  }
    

      public int getVint() {
    
    return vint;
    
  }
    

      public void setVint(int vint) {
    
    this.vint = vint;
    
  }
    

      public long getVlong() {
    
    return vlong;
    
  }
    

      public void setVlong(long vlong) {
    
    this.vlong = vlong;
    
  }
    

      public float getVfloat() {
    
    return vfloat;
    
  }
    

      public void setVfloat(float vfloat) {
    
    this.vfloat = vfloat;
    
  }
    

      public double getVdouble() {
    
    return vdouble;
    
  }
    

      public void setVdouble(double vdouble) {
    
    this.vdouble = vdouble;
    
  }
    

      public boolean isVboolean() {
    
    return vboolean;
    
  }
    

      public void setVboolean(boolean vboolean) {
    
    this.vboolean = vboolean;
    
  }
    

      public Date getDddd() {
    
    return dddd;
    
  }
    

      public void setDddd(Date dddd) {
    
    this.dddd = dddd;
    
  }
    

      public Date getV_Date() {
    
    return v_Date;
    
  }
    

      public void setV_Date(Date v_Date) {
    
    this.v_Date = v_Date;
    
  }
    

      public Date getvDate() {
    
    return vDate;
    
  }
    

      public void setvDate(Date vDate) {
    
    this.vDate = vDate;
    
  }
    

      public Object getVnull() {
    
    return vnull;
    
  }
    

      public void setVnull(Object vnull) {
    
    this.vnull = vnull;
    
  }
    

      public String[] getAvString() {
    
    return avString;
    
  }
    

      public void setAvString(String[] avString) {
    
    this.avString = avString;
    
  }
    

      public int[] getAvint() {
    
    return avint;
    
  }
    

      public void setAvint(int[] avint) {
    
    this.avint = avint;
    
  }
    

      public boolean[] getAvboolean() {
    
    return avboolean;
    
  }
    

      public void setAvboolean(boolean[] avboolean) {
    
    this.avboolean = avboolean;
    
  }
    

      public List<String> getListString() {
    
    return listString;
    
  }
    

      public void setListString(List<String> listString) {
    
    this.listString = listString;
    
  }
    

      public Map<String, String> getMap() {
    
    return map;
    
  }
    

      public void setMap(Map<String, String> map) {
    
    this.map = map;
    
  }
    

      public Bar getBar() {
    
    return bar;
    
  }
    

      public void setBar(Bar bar) {
    
    this.bar = bar;
    
  }
    

      public Bar[] getAvBar() {
    
    return avBar;
    
  }
    

      public void setAvBar(Bar[] avBar) {
    
    this.avBar = avBar;
    
  }
    

      public List<Bar> getListBar() {
    
    return listBar;
    
  }
    

      public void setListBar(List<Bar> listBar) {
    
    this.listBar = listBar;
    
  }
    
}

    package lavasoft.stu.json; 

    import com.alibaba.fastjson.JSON;
    
import com.alibaba.fastjson.serializer.SerializeConfig;
    
import com.alibaba.fastjson.serializer.SimpleDateFormatSerializer;
    

    import java.util.Date;
    
import java.util.Random;
    

    /**
    

      

    • Created by IntelliJ IDEA.
      • 

    • 

    • @author leizhimin 11-11-22 上午9:15
      
*/
      
public class Bar {
      
  public static SerializeConfig mapping = new SerializeConfig();
      
  private String barName;
      
  private int barAge;
      
  private Date barDate = new Date();
      
  static {
      
    mapping.put(Date.class, new SimpleDateFormatSerializer("yyyy-MM-dd"));
      
  }
      
  {
      
    Random r = new Random();
      
    barName = "sss_"+String.valueOf(r.nextFloat());
      
    barAge = r.nextInt();
      
  }
      • 

    

      public static void main(String[] args) {
    
    Object obj = JSON.toJSON(new Bar());
    
    String x1 = JSON.toJSONString(new Bar(), true);
    
    System.out.println(x1);
    
    String x2 = JSON.toJSONString(new Bar(), mapping);
    
    System.out.println(x2);
    
  }
    

      public String getBarName() {
    
    return barName;
    
  }
    

      public void setBarName(String barName) {
    
    this.barName = barName;
    
  }
    

      public int getBarAge() {
    
    return barAge;
    
  }
    

      public void setBarAge(int barAge) {
    
    this.barAge = barAge;
    
  }
    

      public Date getBarDate() {
    
    return barDate;
    
  }
    

      public void setBarDate(Date barDate) {
    
    this.barDate = barDate;
    
  }
    

      @Override
    
  public String toString() {
    
    return "Bar{" +
    
        "barName='" + barName + ''' +
    
        ", barAge=" + barAge +
    
        ", barDate=" + barDate +
    
        '}';
    
  }
    
}

    package lavasoft.stu.json; 

    import com.alibaba.fastjson.JSON;
    
import com.alibaba.fastjson.JSONArray;
    
import com.alibaba.fastjson.serializer.SerializeConfig;
    
import com.alibaba.fastjson.serializer.SimpleDateFormatSerializer;
    

    import java.util.*;
    

    /**
    

      

    • Created by 2IntelliJ IDEA.
      • 

    • 

    • @author leizhimin 11-11-22 上午9:45
      
*/
      
public class Test {
      
  private static SerializeConfig mapping = new SerializeConfig(); static {
      
    mapping.put(Date.class, new SimpleDateFormatSerializer("yyyy-MM-dd HH:mm:ss"));
      
  }
      • 

    

      public static void main(String[] args) {
    
    Foo f1 = new Foo();
    
    Date date = new Date();
    
    String text = JSON.toJSONString(date, mapping);
    
    System.out.println(text);
    
    System.out.println(JSON.toJSONString(f1, true));
    
    String x2 =JSON.toJSONString(f1, mapping);
    
    System.out.println(x2);
    
  }
    

      public static void json2List(){
    
    //List -> JSON array
    
    List<Bar> barList = new ArrayList<Bar>();
    
    barList.add(new Bar());
    
    barList.add(new Bar());
    
    barList.add(new Bar());
    
    String json= JSON.toJSONString(barList, true);
    
    System.out.println(json);
    
    //JSON array -> List
    
    List<Bar> barList1 = JSON.parseArray(json,Bar.class);
    
    for (Bar bar : barList1) {
    
      System.out.println(bar.toString());
    
    }
    
  }
    

      public static void json2Map(){
    
    //Map -> JSON
    
    Map<String,Bar> map = new HashMap<String, Bar>();
    
    map.put("a",new Bar());
    
    map.put("b",new Bar());
    
    map.put("c",new Bar());
    
    String json = JSON.toJSONString(map,true);
    
    System.out.println(json);
    
    //JSON -> Map
    
    Map<String,Bar> map1 = (Map<String,Bar>)JSON.parse(json);
    
    for (String key : map1.keySet()) {
    
      System.out.println(key+":"+map1.get(key));
    
    }
    
  }
    

      public static void array2JSON(){
    
    String[] arr_String    = {"a","b","c"};
    
    String json_arr_String = JSON.toJSONString(arr_String,true);
    
    System.out.println(json_arr_String);
    
    JSONArray jsonArray = JSON.parseArray(json_arr_String);
    
    for (Object o : jsonArray) {
    
      System.out.println(o);
    
    }
    
    System.out.println(jsonArray);
    
  }
    
  public static void array2JSON2(){
    
    Bar[] arr_Bar    = {new Bar(),new Bar(),new Bar()};
    
    String json_arr_Bar = JSON.toJSONString(arr_Bar,true);
    
    System.out.println(json_arr_Bar);
    
    JSONArray jsonArray = JSON.parseArray(json_arr_Bar);
    
    for (Object o : jsonArray) {
    
      System.out.println(o);
    
    }
    
    System.out.println(jsonArray);
    
  }
    

      public static void map2JSON(){
    
    Map map = new HashMap();
    
    map.put("a","aaa");
    
    map.put("b","bbb");
    
    map.put("c","ccc");
    
    String json=JSON.toJSONString(map);
    
    System.out.println(json);
    
    Map map1 = JSON.parseObject(json);
    
    for (Object o : map.entrySet()) {
    
      Map.Entry<String,String> entry = (Map.Entry<String,String>)o;
    
      System.out.println(entry.getKey()+"--->"+entry.getValue());
    
    }
    
  }
    
}

    说明：

    SerializeConfig：是对序列化过程中一些序列化过程的特殊配置，这里用作日期格式的定义。

    有关需要带类型的全类型序列化过程，需要调用JSON.toJSONStringZ()方法。

    需要美化输出时候，需要打开序列化美化开关，在方法中true那个参数。

    输出结果：
    "2011-11-23 23:30:33" 
{ 
  "avBar":[{ 
    "barAge":174398800, 
    "barDate":1322062233062, 
    "barName":"sss_0.62378174" 
  },{ 
    "barAge":38938962, 
    "barDate":1322062233062, 
    "barName":"sss_0.36014742" 
  }], 
  "avString":["aaa","bbb","ccc"], 
  "avboolean":[true,false,true,true], 
  "avint":[1,2,3,4], 
  "bar":{ 
    "barAge":1601495948, 
    "barDate":1322062233062, 
    "barName":"sss_0.46644872" 
  }, 
  "dddd":1322062233046, 
  "listBar":[ 
    { 
      "barAge":-1090113522, 
      "barDate":1322062233062, 
      "barName":"sss_0.83562374" 
    }, 
    { 
      "barAge":478603194, 
      "barDate":1322062233062, 
      "barName":"sss_0.59483266" 
    }, 
    { 
      "barAge":1118357669, 
      "barDate":1322062233062, 
      "barName":"sss_0.9961642" 
    } 
  ], 
  "listString":[ 
    "listString1", 
    "listString2", 
    "listString3" 
  ], 
  "map":{"x":"s11111x","y":"s22222y","z":"s33333z"}, 
  "v_Date":1322062233046, 
  "vboolean":false, 
  "vbyte":64, 
  "vchar":"x", 
  "vdouble":22.203, 
  "vfloat":12.1, 
  "vint":65535, 
  "vlong":9999999, 
  "vshort":128 
} 
{"avBar":[{"barAge":174398800,"barDate":"2011-11-23 23:30:33","barName":"sss_0.62378174"},{"barAge":38938962,"barDate":"2011-11-23 23:30:33","barName":"sss_0.36014742"}],"avString":["aaa","bbb","ccc"],"avboolean":[true,false,true,true],"avint":[1,2,3,4],"bar":{"barAge":1601495948,"barDate":"2011-11-23 23:30:33","barName":"sss_0.46644872"},"dddd":"2011-11-23 23:30:33","listBar":[{"barAge":-1090113522,"barDate":"2011-11-23 23:30:33","barName":"sss_0.83562374"},{"barAge":478603194,"barDate":"2011-11-23 23:30:33","barName":"sss_0.59483266"},{"barAge":1118357669,"barDate":"2011-11-23 23:30:33","barName":"sss_0.9961642"}],"listString":["listString1","listString2","listString3"],"map":{"x":"s11111x","y":"s22222y","z":"s33333z"},"v_Date":"2011-11-23 23:30:33","vboolean":false,"vbyte":64,"vchar":"x","vdouble":22.203,"vfloat":12.1,"vint":65535,"vlong":9999999,"vshort":128} 

    Process finished with exit code 0

    测试小例子：

    JSONObject json = new JSONObject();
json.put("aa", "11");
json.put("bb", "22");
json.put("cc", "33");
String jsonStr = json.toString();
System.out.println(jsonStr);
// {"aa":"11","bb":"22","cc":"33"}	
  
System.out.println(JSONObject.parseObject(jsonStr).get("aa"));
// 11

    String o = "{'area':{'area':'1','pagetype':'home'},'pagetype':'home'}";
    
System.out.println(((Map) JSONObject.parseObject(o).get("area")).get("area"));
    
// 1
    
String text = JSON.toJSONString(o);
    
Map<String, Object> userMap =
    
    JSON.parseObject(o, new TypeReference<Map<String, Object>>() {});
    
System.out.println(((Map) userMap.get("area")).get("NotExsit"));
    
// null
    

    System.out.println(JSON.toJSONString((Map) userMap.get("area")));
    
// {"area":"1","pagetype":"home"}

    fastjson通过各方面测试都很好，功能性能都是No.1，喜欢，它的源代码质量很高，作者也煞费苦心，将性能做到了最好，全免超越其他的json类库。

    从其中的源代码中，可以学到很多东西，在阅读源码后，不得不佩服作者高超的程序设计水平，和高质量的编码。
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  • 原文地址：https://www.cnblogs.com/jpfss/p/9441734.html
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