Jackson 高效能的JSON處理 android/移動開發必備jackson

  今天自行研究了下json ，感覺非常好用，經過測試比google的GSON快多了

      同時Jackson可以輕鬆的將Java對象轉換成json對象和xml文檔，同樣也可以將json、xml轉換成Java對象。功能非常的強悍！

       大家也知道，json 在如今互連網時代應用的非常廣，因為大家如此的關注，所以對json的解析效能要求也是非常高的。

 

一、 準備工作

1、 下載依賴庫jar包

Jackson的jar all：http://jackson.codehaus.org/1.7.6/jackson-all-1.7.6.jar

然後在工程中匯入這個jar包即可開始工作

官方樣本：http://wiki.fasterxml.com/JacksonInFiveMinutes

因為下面的程式是用junit測試案例啟動並執行，所以還得添加junit的jar包。版本是junit-4.2.8

如果你需要轉換xml，那麼還需要stax2-api.jar

2、 測試類別基本代碼如下

 

/* * @project java * @package  * @file Jackson.java * @version  1.0 * @author   廖益平 * @time  2011-11-8 上午02:59:37 */public class Jackson {/* * * Class Descripton goes here. * * @class Jackson * @version  1.0 * @author   廖益平 * @time  2011-11-8 上午02:59:37 */public  static JsonGenerator jsonGenerator = null;private static ObjectMapper mapper = new ObjectMapper();public static void main(String[] args) {Student student = new Student();student.setIsstudent(true);student.setUid(1000);student.setUname("xiao liao");student.setUpwd("123");student.setNumber(12);Map<String, Student> stuMap = new HashMap<String, Student>();stuMap.put("1", student);stuMap.put("2", student);List<Object> stuList = new ArrayList<Object>();List<Student> stuList1 = new ArrayList<Student>();stuList1.add(student);student=  new  Student();student.setIsstudent(false);student.setUid(200);student.setUname("xiao mi");stuList1.add(student);stuList.add(student);stuList.add("xiao xin");stuList.add("xiao er");stuList.add(stuMap);//readJson2List();try {//readJson2Array();//writeArray2Json(array);//writeJson2List();//writeEntity2Json(student);writeJson2Entity();//writeMap2Json(stuMap);//writeList2Json(stuList1);} catch (IOException e) {e.printStackTrace();}} /**  *   * <code>writeEntity2Json</code>  * @description: TODO(實體類轉換成json)   * @param object  * @throws IOException  * @since   2011-11-8     廖益平  */ public static void writeEntity2Json(Object object) throws IOException {   mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"),object );   mapper.writeValue( System.out,object );  } /**  *   * <code>writeArray2Json</code>  * @description: TODO(數群組轉換成json數組)   * @param object  * @throws IOException  * @since   2011-11-8     廖益平  */ public static void writeArray2Json(Object object) throws IOException {  // writeValue具有和writeObject相同的功能 mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"),object ); mapper.writeValue(System.out,object );  } /**  *   * <code>writeMap2Json</code>  * @description: TODO(map對象轉換成json對象)   * @param object  * @throws IOException  * @since   2011-11-8     廖益平  */ public static void writeMap2Json(Object object) throws IOException {  System.out.println("使用ObjectMapper-----------"); // writeValue具有和writeObject相同的功能 System.out.println("==>"+mapper.writeValueAsString(object)); mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aamap.txt"),object ); mapper.writeValue( System.out , object ); } /**  *   * <code>writeList2Json</code>  * @description: TODO(list轉換成json)   * @param object  * @throws IOException  * @since   2011-11-8     廖益平  */ public static void writeList2Json(Object object) throws IOException { System.out.println("==>"+mapper.writeValueAsString(object)); mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aamap.txt"),object ); mapper.writeValue( System.out , object ); } /**  *   * <code>writeJson2Entity</code>  * @description: TODO(json轉換成實體)   * @throws IOException  * @since   2011-11-8     廖益平  */ public static void writeJson2Entity() throws IOException { System.out.println("json串轉換成entity-------------");// File file = new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt");// FileInputStream inputStream = new FileInputStream(file);// Student student = mapper.readValue(inputStream,Student.class);// System.out.println(student.toString()); //漂亮輸出 //mapper.defaultPrettyPrintingWriter().writeValueAsString(value); String json = "{\"uid\":1000,\"uname\":\"xiao liao\",\"upwd\":\"123\",\"number\":12.0,\"isstudent\":true}"; Student student1 = mapper.readValue(json,Student.class); System.out.println("json2:"+student1.toString()); } /**  *   * <code>writeJson2List</code>  * @description: TODO(json專程list對象)   * @throws IOException  * @since   2011-11-8     廖益平  */ public static void writeJson2List() throws IOException { System.out.println("json串轉換成entity-------------"); File file = new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"); FileInputStream inputStream = new FileInputStream(file); Student student = mapper.readValue(inputStream,Student.class); System.out.println(student.toString());  String json = "[{\"uid\":1000,\"uname\":\"xiao liao\",\"upwd\":\"123\",\"number\":12.0,\"isstudent\":true},{\"uid\":200,\"uname\":\"xiao mi\",\"upwd\":null,\"number\":0.0,\"isstudent\":false}]"; List<LinkedHashMap<String, Object>> s= mapper.readValue(json,List.class); for (int i = 0; i < s.size(); i++) { LinkedHashMap<String, Object> link = s.get(i); Set<String>  key = link.keySet(); for (Iterator iterator = key.iterator(); iterator.hasNext();) {String string = (String) iterator.next();System.out.println(string+"==>"+link.get(string));} System.out.println("json:"+i+""+s.get(i).toString());} } /**   * JSON轉換為List對象   */  public static void readJson2List() {   String json = "[{\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\"},"     + "{\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"}]";   try {    List<LinkedHashMap<String, Object>> list = mapper.readValue(      json, List.class);    System.out.println(list.size());    for (int i = 0; i < list.size(); i++) {     Map<String, Object> map = list.get(i);     Set<String> set = map.keySet();     for (Iterator<String> it = set.iterator(); it.hasNext();) {      String key = it.next();      System.out.println(key + ":" + map.get(key));     }    }   } catch (JsonParseException e) {    e.printStackTrace();   } catch (JsonMappingException e) {    e.printStackTrace();   } catch (IOException e) {    e.printStackTrace();   }  }  /**   * JSON轉換為List對象   */  public static void readJson2Array() {  String json = "[{\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\"},"  + "{\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"}]";  try {  Student[] students = mapper.readValue(json, Student[].class);  for (Student student : students) {System.out.println(">"+student.toString());}  } catch (JsonParseException e) {  e.printStackTrace();  } catch (JsonMappingException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  }}

列印結果 ：

串轉換成entity-------------
json2:uid=1000,name=xiao liao,upwd=123,number=12.0,isStudent=true

writeMap2Json -----------
{"2":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true},"1":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true}}

readJson2Array------------------
>uid=1,name=www,upwd=456,number=234.0,isStudent=false
>uid=5,name=tom,upwd=123,number=3.44,isStudent=false
writeMap2Json -----------
{"2":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true},"1":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true}}

大家逐個自己試試吧  ，上面也是我的測試代碼

 

實體類：/* * @project java * @package  * @file Student.java * @version  1.0 * @author   廖益平 * @time  2011-11-8 上午03:01:08 */public class Student {/* * * Class Descripton goes here. * * @class Student * @version  1.0 * @author   廖益平 * @time  2011-11-8 上午03:01:08 */  private int uid;  private String uname;  private String upwd;  private double number;  private boolean isstudent;public int getUid() {return uid;}public void setUid(int uid) {this.uid = uid;}public String getUname() {return uname;}public void setUname(String uname) {this.uname = uname;}public String getUpwd() {return upwd;}public void setUpwd(String upwd) {this.upwd = upwd;}public double getNumber() {return number;}public void setNumber(double number) {this.number = number;}public boolean isIsstudent() {return isstudent;}public void setIsstudent(boolean isstudent) {this.isstudent = isstudent;}@Overridepublic String toString() {return "uid="+uid+",name="+uname+",upwd="+upwd+",number="+number+",isStudent="+isstudent;}  }