fastJson API

「爱情、让人受尽委屈。」 2022-08-27 15:48 150阅读 0赞

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][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][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][http_code.alibabatech.com_wiki_display_FastJSON_Home]

如果获得Fastjson？  
SVN: [http://code.alibabatech.com/svn/fastjson/trunk/][http_code.alibabatech.com_svn_fastjson_trunk]  
WIKI: [http://code.alibabatech.com/wiki/display/FastJSON/Home][http_code.alibabatech.com_wiki_display_FastJSON_Home]  
Issue Tracking: [http://code.alibabatech.com/jira/browse/FASTJSON][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.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

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。

[http_www.json.org_json-zh.html]: http://www.json.org/json-zh.html
[http_json.org]: http://json.org/
[http_code.alibabatech.com_wiki_display_FastJSON_Home]: http://code.alibabatech.com/wiki/display/FastJSON/Home
[http_code.alibabatech.com_svn_fastjson_trunk]: http://code.alibabatech.com/svn/fastjson/trunk/
[http_code.alibabatech.com_jira_browse_FASTJSON]: http://code.alibabatech.com/jira/browse/FASTJSON