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 = newDate();

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"));

}

{

Randomr = new Random();

barName= "sss_"+String.valueOf(r.nextFloat());

barAge= r.nextInt();

}

public static void main(String[] args) {

Objectobj = JSON.toJSON(new Bar());

Stringx1 = JSON.toJSONString(new Bar(), true);

System.out.println(x1);

Stringx2 = 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-ddHH:mm:ss"));

}

public static void main(String[] args) {

Foof1 = new Foo();

Datedate = new Date();

Stringtext = JSON.toJSONString(date, mapping);

System.out.println(text);

System.out.println(JSON.toJSONString(f1, true));

Stringx2 =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());

Stringjson= 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());

Stringjson = 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"};

Stringjson_arr_String = JSON.toJSONString(arr_String,true);

System.out.println(json_arr_String);

JSONArrayjsonArray = 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()};

Stringjson_arr_Bar = JSON.toJSONString(arr_Bar,true);

System.out.println(json_arr_Bar);

JSONArrayjsonArray = JSON.parseArray(json_arr_Bar);

for (Object o : jsonArray) {

System.out.println(o);

}

System.out.println(jsonArray);

}

public static void map2JSON(){

Mapmap = new HashMap();

map.put("a","aaa");

map.put("b","bbb");

map.put("c","ccc");

Stringjson=JSON.toJSONString(map);

System.out.println(json);

Mapmap1 = 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":"2011-11-2323:30:33","barName":"sss_0.62378174"},{"barAge":38938962,"barDate":"2011-11-2323:30:33","barName":"sss_0.36014742"}],"avString":["aaa","bbb","ccc"],"avboolean":[true,false,true,true],"avint":[1,2,3,4],"bar":{"barAge":1601495948,"barDate":"2011-11-2323:30:33","barName":"sss_0.46644872"},"dddd":"2011-11-2323:30:33","listBar":[{"barAge":-1090113522,"barDate":"2011-11-2323:30:33","barName":"sss_0.83562374"},{"barAge":478603194,"barDate":"2011-11-2323:30:33","barName":"sss_0.59483266"},{"barAge":1118357669,"barDate":"2011-11-2323:30:33","barName":"sss_0.9961642"}],"listString":["listString1","listString2","listString3"],"map":{"x":"s11111x","y":"s22222y","z":"s33333z"},"v_Date":"2011-11-2323:30:33","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。