Gson实际应用

有时项目中对json有特殊的格式规定.比如下面的json串解析:

[{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:54:49 PM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 9:54:49 PM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 9:54:49 PM"}]},{"tableName":"teachers","tableData":[{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲师"}]}]

分析之后我们发现使用前面博客中用到的都不好处理上面的json串.请看本文是如何处理的吧:

实体类:

 import java.util.Date;

 public class Student {
     private int id;
     private String name;
     private Date birthDay;

     public int getId() {
         return id;
     }

     public void setId(int id) {
         this.id = id;
     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public Date getBirthDay() {
         return birthDay;
     }

     public void setBirthDay(Date birthDay) {
         this.birthDay = birthDay;
     }

     @Override
     public String toString() {
         return "Student [birthDay=" + birthDay + ", id=" + id + ", name="
                 + name + "]";
     }

 }

 public class Teacher {
     private int id;

     private String name;

     private String title;

     public int getId() {
         return id;
     }

     public void setId(int id) {
         this.id = id;
     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public String getTitle() {
         return title;
     }

     public void setTitle(String title) {
         this.title = title;
     }

     @Override
     public String toString() {
         return "Teacher [id=" + id + ", name=" + name + ", title=" + title
                 + "]";
     }

 }

注意这里定义了一个TableData实体类:

 import java.util.List;

 public class TableData {

     private String tableName;

     private List tableData;

     public String getTableName() {
         return tableName;
     }

     public void setTableName(String tableName) {
         this.tableName = tableName;
     }

     public List getTableData() {
         return tableData;
     }

     public void setTableData(List tableData) {
         this.tableData = tableData;
     }
 }

测试类:

(仔细看将json转回为对象的实现,这里经过两次转化,第一次转回的结果是map不是我们所期望的对象,对map再次转为json后再转为对象,我引用的是Gson2.1的jar处理正常,好像使用Gson1.6的jar会报错,所以建议用最新版本)

 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;

 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;

 public class GsonTest5 {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // 对象转为Json-->start
         Student student1 = new Student();
         student1.setId(1);
         student1.setName("李坤");
         student1.setBirthDay(new Date());

         Student student2 = new Student();
         student2.setId(2);
         student2.setName("曹贵生");
         student2.setBirthDay(new Date());

         Student student3 = new Student();
         student3.setId(3);
         student3.setName("柳波");
         student3.setBirthDay(new Date());

         List<Student> stulist = new ArrayList<Student>();
         stulist.add(student1);
         stulist.add(student2);
         stulist.add(student3);

         Teacher teacher1 = new Teacher();
         teacher1.setId(1);
         teacher1.setName("米老师");
         teacher1.setTitle("教授");

         Teacher teacher2 = new Teacher();
         teacher2.setId(2);
         teacher2.setName("丁老师");
         teacher2.setTitle("讲师");
         List<Teacher> teacherList = new ArrayList<Teacher>();
         teacherList.add(teacher1);
         teacherList.add(teacher2);

         TableData td1 = new TableData();
         td1.setTableName("students");
         td1.setTableData(stulist);

         TableData td2 = new TableData();
         td2.setTableName("teachers");
         td2.setTableData(teacherList);

         List<TableData> tdList = new ArrayList<TableData>();
         tdList.add(td1);
         tdList.add(td2);
         Gson gson = new Gson();
         String s = gson.toJson(tdList);

         System.out.println(s);
         // 结果:[{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 10:44:16 AM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 10:44:16 AM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 10:44:16 AM"}]},{"tableName":"teachers","tableData":[{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲师"}]}]
         // 对象转为Json-->end

         // /////////////////////////////////////////////////////////////////////

         // 将json转为数据-->start
         List<TableData> tableDatas2 = gson.fromJson(s,
                 new TypeToken<List<TableData>>() {
                 }.getType());
         for (int i = 0; i < tableDatas2.size(); i++) {
             TableData entityData = tableDatas2.get(i);
             String tableName = entityData.getTableName();
             List tableData = entityData.getTableData();
             String s2 = gson.toJson(tableData);
             // System.out.println(s2);
             // System.out.println(entityData.getData());
             if (tableName.equals("students")) {
                 System.out.println("students");
                 List<Student> retStuList = gson.fromJson(s2,
                         new TypeToken<List<Student>>() {
                         }.getType());
                 for (int j = 0; j < retStuList.size(); j++) {
                     System.out.println(retStuList.get(j));
                 }

             } else if (tableName.equals("teachers")) {
                 System.out.println("teachers");
                 List<Teacher> retTchrList = gson.fromJson(s2,
                         new TypeToken<List<Teacher>>() {
                         }.getType());
                 for (int j = 0; j < retTchrList.size(); j++) {
                     System.out.println(retTchrList.get(j));
                 }
             }
         }

         // Json转为对象-->end
     }
 }

输出结果:

 [{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 10:04:12 PM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 10:04:12 PM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 10:04:12 PM"}]},{"tableName":"teachers","tableData":[{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲师"}]}]
 students
 Student [birthDay=Fri Jun 22 22:04:12 CST 2012, id=1, name=李坤]
 Student [birthDay=Fri Jun 22 22:04:12 CST 2012, id=2, name=曹贵生]
 Student [birthDay=Fri Jun 22 22:04:12 CST 2012, id=3, name=柳波]
 teachers
 Teacher [id=1, name=米老师, title=教授]
 Teacher [id=2, name=丁老师, title=讲师]

其实就是多次使用，进行解析。

转自：http://blog.csdn.net/lk_blog/article/details/7685237