Json轉換利器Gson之實例五-實際開發中的特殊需求處理(手動解析-TypeToken)

前面四篇博客基本上可以滿足我們處理的絕大多數需求,但有時項目中對json有特殊的格式規定.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":"曹貴生","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":"米老師","title":"教授"},{"id":2,"name":"丁老師","title":"講師"}]}]

分析之後我們發現使用前面博客中用到的都不好處理上面的json串.請看本文是如何處理的吧:

實體類:

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
                + "]";
    }

}

注意這裏定義了一個TableData實體類:

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;
    }
}

測試類:

(仔細看將json轉回爲對象的實現,這裏經過兩次轉化,第一次轉回的結果是map不是我們所期望的對象,對map再次轉爲json後再轉爲對象,我引用的是Gson2.1的jar處理正常,好像使用Gson1.6的jar會報錯,所以建議用最新版本)

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) {
        // 對象轉爲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("曹貴生");
        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("米老師");
        teacher1.setTitle("教授");

        Teacher teacher2 = new Teacher();
        teacher2.setId(2);
        teacher2.setName("丁老師");
        teacher2.setTitle("講師");
        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);
        // 結果:[{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 10:44:16 AM"},{"id":2,"name":"曹貴生","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":"米老師","title":"教授"},{"id":2,"name":"丁老師","title":"講師"}]}]
        // 對象轉爲Json-->end

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

        // 將json轉爲數據-->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轉爲對象-->end
    }
}

輸出結果:

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

轉自：http://blog.csdn.net/lk_blog/article/category/1172246