AsyncTask 异步任务 的用法（并且使用ORMlite关系数据库）；

package com.lixu.asynctask;

import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.table.DatabaseTable;

@DatabaseTable(tableName = "users")
public class User {
    public User() {

    }


    

    @Override
    public String toString() {
        return "id" + user_id + "," + ",姓名：" + name + ",年龄：" + age + ",性别：" + sex+",班级是："+aclass;
    }

    


    public int getUser_id() {
        return user_id;
    }

    public void setUser_id(int user_id) {
        this.user_id = user_id;
    }

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public AClass getAclass() {
        return aclass;
    }

    public void setAclass(AClass aclass) {
        this.aclass = aclass;
    }

    public User(int user_id, String name, int age, String sex, AClass aclass) {
        super();
        this.user_id = user_id;
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.aclass = aclass;
    }


 
    @DatabaseField(id=true,columnName = "user_id")
    public int user_id;

    @DatabaseField(columnName = "name")
    public String name;

    @DatabaseField(columnName = "age")
    public int age;
    @DatabaseField(columnName = "sex")
    public String sex;
    @DatabaseField(canBeNull = false, foreign = true, foreignAutoRefresh = true)
    public AClass aclass;

}

package com.lixu.asynctask;

import com.j256.ormlite.dao.ForeignCollection;
import com.j256.ormlite.field.DataType;
import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.field.ForeignCollectionField;
import com.j256.ormlite.table.DatabaseTable;

@DatabaseTable(tableName = "classes")
public class AClass {

    public AClass(long id, String name, ForeignCollection<User> user) {
        super();
        this.id = id;
        this.name = name;
        this.user = user;
    }

    @Override
    public String toString() {
        return "id" + id + "班级名：" + name;
    }

    public long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public ForeignCollection<User> getUser() {
        return user;
    }

    public void setUser(ForeignCollection<User> user) {
        this.user = user;
    }

    @DatabaseField(id = true)
    public long id;

    @DatabaseField(dataType = DataType.STRING)
    public String name;

    @ForeignCollectionField(eager = false)
    public ForeignCollection<User> user = null;

    public AClass() {

    }

}

package com.lixu.asynctask;

import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.dao.Dao;
import com.j256.ormlite.support.ConnectionSource;
import com.j256.ormlite.table.TableUtils;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.util.Log;

public class MyORMlite extends OrmLiteSqliteOpenHelper {
    private static String DATABASENAME = "lixu.db";
    private static int DATABASEVERSION = 1;

    private static MyORMlite mMyORMlite = null;
    private Dao<User, Integer> muserDao = null;
    private Dao<AClass, Integer> mclassDao = null;

    public MyORMlite(Context context, String databaseName, CursorFactory factory, int databaseVersion) {
        super(context, databaseName, factory, databaseVersion);
    }

    public static MyORMlite getInstance(Context context) {
        if (mMyORMlite == null) {
            mMyORMlite = new MyORMlite(context, DATABASENAME, null, DATABASEVERSION);
        }
        return mMyORMlite;

    }

    @Override
    public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {

        try {
            TableUtils.createTableIfNotExists(arg1, User.class);
            TableUtils.createTableIfNotExists(arg1, AClass.class);
            Log.d("MyORMlite", "被创建");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public Dao<User, Integer> getuserDao() {
        if (muserDao == null) {
            try {
                muserDao = getDao(User.class);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return muserDao;
    }

    public Dao<AClass, Integer> getclassDao() {
        if (mclassDao == null) {
            try {
                mclassDao = getDao(AClass.class);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return mclassDao;
    }

    @Override
    public void close() {
        super.close();
        muserDao = null;
        mclassDao = null;
        
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2, int arg3) {

    }

}

package com.lixu.asynctask;

import java.sql.SQLException;
import java.util.List;

import com.j256.ormlite.dao.Dao;
import com.lixu.asynctask.AClass;
import com.lixu.asynctask.User;
import com.lixu.asynctask.MyORMlite;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private Dao<User, Integer> muserDao = null;
    private Dao<AClass, Integer> mclassDao = null;
    TextView tv;
    StringBuffer sb = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        MyORMlite mMyORMlite = MyORMlite.getInstance(this);
        muserDao = mMyORMlite.getuserDao();
        mclassDao = mMyORMlite.getclassDao();

        tv = (TextView) findViewById(R.id.tv);
        tv.setMovementMethod(ScrollingMovementMethod.getInstance());

        Button btn = (Button) findViewById(R.id.button1);
        btn.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                MyTask mMyTask = new MyTask();
                mMyTask.execute();
            }
        });
    }

    // 用一个类继承AsyncTask
    private class MyTask extends AsyncTask {
        // 先执行这个方法 可以处理一些初始化的事件等。
        @Override
        protected void onPreExecute() {
            sb = new StringBuffer();
            super.onPreExecute();
        }

        // 这个方法可以处理相对耗时较长的任务，这个方法里面不可以执行ui任务。
        @Override
        protected Object doInBackground(Object... params) {
            add();
            List<User> list = chaxun();
            for (User n : list) {
                sb.append("姓名是：" + n.getName() + ",性别是：" + n.getSex() + ",班级是：" + n.getAclass().getName() + "
");
            }
            return sb;
        }

        // 可以将上一个方法处理的结果传到这个方法中，并且这个方法里面可以处理ui任务。
        @Override
        protected void onPostExecute(Object params) {
            super.onPostExecute(params);
            tv.setText(params.toString());
            Toast.makeText(MainActivity.this, "显示成功", 0).show();
        }
    }

    public List<User> chaxun() {
        List<User> list = null;
        try {
            list = muserDao.queryForAll();

        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;

    }

    public void add() {

        for (int j = 1; j <= 3; j++) {
            AClass classes = null;
            classes = new AClass();
            classes.setName("大三" + j + "班");
            classes.setId(j);
            try {
                mclassDao.createIfNotExists(classes);
            } catch (SQLException e) {
                e.printStackTrace();
            }
            for (int i = 10 * (j - 1) + 1; i <= 10 * j; i++) {
                User user = new User();
                user.setName("张三" + i);
                user.setAge(20 + i);
                user.setUser_id(i);
                user.setSex("男");
                user.setAclass(classes);// 挂载到class
                try {
                    muserDao.createIfNotExists(user);
                } catch (SQLException e) {
                    e.printStackTrace();
                }

            }
        }

    }
}