关于fastJSON

FastJSON是一个很好的java开源json工具类库，相比其他同类的json类库，它的速度的确是fast，最快！但是文档做得不好，在应用前不得不亲测一些功能。

实际上其他的json处理工具都和它差不多，api也有几分相似。

一、JSON规范

JSON是一个标准规范，用于数据交互，规范的中文文档如下：

http://www.json.org/json-zh.html

参看规范，来对比JSON类库处理结果。

二、fastjson的一些简要说明

1、了解fastjson

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。 http://code.alibabatech.com/wiki/display/FastJSON/Home

如果获得Fastjson？
SVN: http://code.alibabatech.com/svn/fastjson/trunk/
WIKI: http://code.alibabatech.com/wiki/display/FastJSON/Home
Issue Tracking: http://code.alibabatech.com/jira/browse/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。

三、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,
"barName":"sss_0.36014742"
}],
"avString":["aaa","bbb","ccc"],
"avboolean":[true,false,true,true],
"avint":[1,4],
"bar":{
"barAge":1601495948,
"barName":"sss_0.46644872"
},
"dddd":1322062233046,
"listBar":[
{
"barAge":-1090113522,
"barName":"sss_0.83562374"
},
{
"barAge":478603194,
"barName":"sss_0.59483266"
},
{
"barAge":1118357669,
"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,"barName":"sss_0.36014742"}],"avString":["aaa","avboolean":[true,"avint":[1,"bar":{"barAge":1601495948,"barName":"sss_0.46644872"},"dddd":"2011-11-23 23:30:33","listBar":[{"barAge":-1090113522,"barName":"sss_0.83562374"},{"barAge":478603194,"barName":"sss_0.59483266"},{"barAge":1118357669,"barName":"sss_0.9961642"}],"listString":["listString1","listString2","listString3"],"map":{"x":"s11111x","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

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。