Android作为目前主流的移动操作系统，完全符合SQLite占用资源少的优势，故在Android平台上，集成了一个嵌入式关系型数据库—SQLite。如果想要开发 Android 应用程序，需要在 Android 上存储数据，使用SQLite 数据库是一种非常好的选择。在一般程序中使用数据库的过程都可以框架化，套路化，实例如下：

表说明：

1.班级 classes：

   class_id  主键 class_name 

2.学生 students：

   student_id 主键 student_name  score  class_id 外键

创建表：

CREATE TABLE students(student_id varchar(10) primary key ,

                                              foreign key (class_id) references classes(class_id) on delete cascade on update cascade )

1. 继承扩展 SQLiteOpenHelper 创建数据库和对应表

package com.tang.databasedemo;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.util.Log;public class DBHelper extends SQLiteOpenHelper{public DBHelper(Context context) {super(context, "info.db", null, 1);// TODO Auto-generated constructor stub}@Overridepublic void onCreate(SQLiteDatabase db) {// TODO Auto-generated method stubString classesSQL = "CREATE TABLE classes(class_id varchar(10) primary key , " +        "class_name varchar(20))";String studentsSQL = "CREATE TABLE students(student_id varchar(10) primary key , " +        "student_name varchar(20) ,score varchar(4) ,class_id varchar(10), " +        "foreign key (class_id) references classes(class_id) " +        "on delete cascade on update cascade )";db.execSQL(classesSQL);Log.d("my", "create table classes:"+classesSQL);db.execSQL(studentsSQL);Log.d("my", "create table students:"+studentsSQL);}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stub}}

package com.tang.databasedemo;import android.util.Log;public class Class {private String classId;private String className;public String getClassId() {return classId;}public void setClassId(String classId) {this.classId = classId;}public String getClassName() {return className;}public void setClassName(String className) {this.className = className;}public String toString() {return "Class--->"+"classId:"+classId+"  className:"+className;}}

package com.tang.databasedemo;public class Student {private String studentId;private String studentName;private String score;private String classId;public String getStudentId() {return studentId;}public void setStudentId(String studentId) {this.studentId = studentId;}public String getStudentName() {return studentName;}public void setStudentName(String studentName) {this.studentName = studentName;}public String getScore() {return score;}public void setScore(String score) {this.score = score;}public String getClassId() {return classId;}public void setClassId(String classId) {this.classId = classId;}public String  toString() {return "Student--->"+"studentId:"+studentId+" studentName:"+studentName+" score:"+score+" classId:"+classId;}}

3. 创建DBServer类，在该类中定义增删改查等方法来操作数据库

package com.tang.databasedemo;import java.util.ArrayList;import java.util.List;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;public class DBServer {private DBHelper dbhelper;public DBServer(Context context){ this.dbhelper = new DBHelper(context);}/** * 添加班级 * @param entity */public void addClass(Class entity){    SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();  Object[] arrayOfObject = new Object[2];  arrayOfObject[0] = entity.getClassId();  arrayOfObject[1] = entity.getClassName();  localSQLiteDatabase.execSQL("insert into classes(class_id,class_name) values(?,?)", arrayOfObject);  localSQLiteDatabase.close();}/** * 添加学生 * @param entity */public void addStudent(Student entity){    SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();  Object[] arrayOfObject = new Object[4];  arrayOfObject[0] = entity.getStudentId();  arrayOfObject[1] = entity.getStudentName();  arrayOfObject[2] = entity.getScore();  arrayOfObject[3] = entity.getClassId();  localSQLiteDatabase.execSQL("insert into students(student_id,student_name,score,class_id) values(?,?,?,?)", arrayOfObject);  localSQLiteDatabase.close();}/** * 删除一个班级 * 同时会删除students中该班级的学生 * @param class_id */public void deleteClass(String class_id){    SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();    //设置了级联删除和级联更新    //在执行有级联关系的语句的时候必须先设置“PRAGMA foreign_keys=ON”    //否则级联关系默认失效    localSQLiteDatabase.execSQL("PRAGMA foreign_keys=ON");    Object[] arrayOfObject = new Object[1];    arrayOfObject[0] =class_id;    localSQLiteDatabase.execSQL("delete from classes where class_id=?", arrayOfObject);    localSQLiteDatabase.close();}/** * 删除一个学生 * @param student_id */public void deleteStudent(String student_id){    SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();    Object[] arrayOfObject = new Object[1];    arrayOfObject[0] =student_id;    localSQLiteDatabase.execSQL("delete from students where student_id=?", arrayOfObject);    localSQLiteDatabase.close();}/** * 修改学生信息* @param entity*/   public void updateStudentInfo(Student entity)   {   SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();   Object[] arrayOfObject = new Object[4];      arrayOfObject[0] = entity.getStudentName();   arrayOfObject[1] = entity.getScore();   arrayOfObject[2] = entity.getClassId();   arrayOfObject[3] = entity.getStudentId();      localSQLiteDatabase.execSQL("update students set student_name=?,score=?,class_id=?  where student_id=?", arrayOfObject);   localSQLiteDatabase.close();   }/** * 使用班级编号查找该班级所有学生 * @param classId * @return */public List findStudentsByClassId(String classId){  List localArrayList=new ArrayList();  SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();      Cursor localCursor = localSQLiteDatabase.rawQuery("select student_id, student_name ,score  from students  " +  "where class_id=?  order by score desc", new String[]{classId});   while (localCursor.moveToNext())  {  Student temp=new Student();  temp.setStudentId(localCursor.getString(localCursor.getColumnIndex("student_id")));  temp.setStudentName(localCursor.getString(localCursor.getColumnIndex("student_name")));  temp.setScore(localCursor.getString(localCursor.getColumnIndex("score")));  temp.setClassId(classId);      localArrayList.add(temp);  }  localSQLiteDatabase.close();  return localArrayList; }/** * 使用班级名查找该班级所有学生 * @param className * @return */public List findStudentsByClassName(String className){  List localArrayList=new ArrayList();  SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();      Cursor localCursor = localSQLiteDatabase.rawQuery("select student_id, student_name,score,classes.class_id from students,classes" +  " where students.class_id=classes.class_id and classes.class_name =?  order by score asc" , new String[]{className});   while (localCursor.moveToNext())  {  Student temp=new Student();  temp.setStudentId(localCursor.getString(localCursor.getColumnIndex("student_id")));  temp.setStudentName(localCursor.getString(localCursor.getColumnIndex("student_name")));  temp.setScore(localCursor.getString(localCursor.getColumnIndex("score")));  temp.setClassId(localCursor.getString(3));      localArrayList.add(temp);  }  localSQLiteDatabase.close();  return localArrayList; }/** * 查找所有学生 * @param className * @return */public List findAllStudents(){  List localArrayList=new ArrayList();  SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();      Cursor localCursor = localSQLiteDatabase.rawQuery("select * from students " +  "where 1=1  order by score desc ", null);  while (localCursor.moveToNext())  {  Student temp=new Student();  temp.setStudentId(localCursor.getString(localCursor.getColumnIndex("student_id")));  temp.setStudentName(localCursor.getString(localCursor.getColumnIndex("student_name")));  temp.setScore(localCursor.getString(localCursor.getColumnIndex("score")));  temp.setClassId(localCursor.getString(localCursor.getColumnIndex("class_id")));      localArrayList.add(temp);  }  localSQLiteDatabase.close();  return localArrayList; }/** * 取得所有班级 * @return */public List findAllClasses(){  List localArrayList=new ArrayList();  SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();      Cursor localCursor = localSQLiteDatabase.rawQuery("select * from classes " +  "where 1=1", null);  while (localCursor.moveToNext())  {  Class temp=new Class();  temp.setClassId(localCursor.getString(localCursor.getColumnIndex("class_id")));  temp.setClassName(localCursor.getString(localCursor.getColumnIndex("class_name")));      localArrayList.add(temp);  }  localSQLiteDatabase.close();  return localArrayList; }/** * 成绩最好 * @return */public Student findMaxScoreStudent(){Student temp =new Student();SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();    Cursor localCursor = localSQLiteDatabase.rawQuery("select student_id,student_name,class_id,max(score)  from students  " +  "where 1=1",null );localCursor.moveToFirst();temp.setStudentId(localCursor.getString(0));temp.setStudentName(localCursor.getString(1));temp.setClassId(localCursor.getString(2));temp.setScore(localCursor.getString(3));return temp;}/** * 查找是否有该学生 * @param studentId * @return */public boolean isStudentsExists(String studentId){  SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();      Cursor localCursor = localSQLiteDatabase.rawQuery("select count(*)  from students  " +  "where student_id=?", new String[]{studentId});  localCursor.moveToFirst();  if(localCursor.getLong(0)>0)  return true;  else  return false; }/** * 确认该班级是否存在 * @param classId * @return */public boolean isClassExists(String s){  SQLiteDatabase localSQLiteDatabase = this.dbhelper.getWritableDatabase();      Cursor localCursor = localSQLiteDatabase.rawQuery("select count(*)  from classes  " +  "where class_id=? or class_name=?", new String[]{s,s});  localCursor.moveToFirst();  if(localCursor.getLong(0)>0)  return true;  else  return false; }}

4.调用DBServer里的方法，操作数据

package com.tang.databasedemo;import java.util.ArrayList;import java.util.List;import java.util.Random;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.app.Activity;import android.app.AlertDialog;import android.app.Dialog;import android.content.DialogInterface;import android.content.SharedPreferences;import android.text.AlteredCharSequence;import android.util.Log;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class MainActivity extends Activity implements OnClickListener {private List classData =new ArrayList();private List studentsData =new ArrayList();private static final String className ="A/B/C/D/E";private static final String studentName ="彭大/黄二/张三/李四/王五/郑六/田七/周八/叶九/孔十/萧十一";private DBServer db;private SharedPreferences share;private SharedPreferences.Editor editor;private String info ="";private EditText editText;private Button b,b1,b2,b3,b4,b5,b6;private EditText sId,sName,score,cId,cName;private Handler hander =new Handler(){@Overridepublic void handleMessage(Message msg) {// TODO Auto-generated method stubif(msg.what==0){sId.setText("");sName.setText("");score.setText("");cName.setText("");cId.setText("");}else if(msg.what==1){db.deleteClass((String)msg.obj);info += "删除一个班级及班级里面的学生：班级Id:"+(String)msg.obj;editText.setText(info);}}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();share = getSharedPreferences("DatabaseDamo", 0);editor =share.edit();db=new DBServer(this);if(share.getInt("times", 0)==0){initDatabase();editor.putInt("times", 1);editor.commit();}}private void initView(){editText = (EditText) findViewById(R.id.info);sId = (EditText) findViewById(R.id.studentId);sName = (EditText) findViewById(R.id.studentName);score = (EditText) findViewById(R.id.score);cId = (EditText) findViewById(R.id.classId);cName = (EditText) findViewById(R.id.className);b =(Button) findViewById(R.id.button);b1 =(Button) findViewById(R.id.button1);b2 =(Button) findViewById(R.id.button2);b3 =(Button) findViewById(R.id.button3);b4 =(Button) findViewById(R.id.button4);b5 =(Button) findViewById(R.id.button5);b6 =(Button) findViewById(R.id.button6);b.setOnClickListener(this);b1.setOnClickListener(this);b2.setOnClickListener(this);b3.setOnClickListener(this);b4.setOnClickListener(this);b5.setOnClickListener(this);b6.setOnClickListener(this);}private void initDatabase(){info="";editText.setText("");String []classTemp = className.split("/");Class c;for(int i=0;i

 /**     * Create and/or open a database that will be used for reading and writing.     * The first time this is called, the database will be opened and     * {@link #onCreate}, {@link #onUpgrade} and/or {@link #onOpen} will be     * called.     *     * 
Once opened successfully, the database is cached, so you can     * call this method every time you need to write to the database.     * (Make sure to call {@link #close} when you no longer need the database.)     * Errors such as bad permissions or a full disk may cause this method     * to fail, but future attempts may succeed if the problem is fixed.
     *     * 
Database upgrade may take a long time, you     * should not call this method from the application main thread, including     * from {@link android.content.ContentProvider#onCreate ContentProvider.onCreate()}.     *     * @throws SQLiteException if the database cannot be opened for writing     * @return a read/write database object valid until {@link #close} is called     */    public SQLiteDatabase getWritableDatabase() {        synchronized (this) {            return getDatabaseLocked(true);        }    }    /**     * Create and/or open a database.  This will be the same object returned by     * {@link #getWritableDatabase} unless some problem, such as a full disk,     * requires the database to be opened read-only.  In that case, a read-only     * database object will be returned.  If the problem is fixed, a future call     * to {@link #getWritableDatabase} may succeed, in which case the read-only     * database object will be closed and the read/write object will be returned     * in the future.     *     * 
Like {@link #getWritableDatabase}, this method may     * take a long time to return, so you should not call it from the     * application main thread, including from     * {@link android.content.ContentProvider#onCreate ContentProvider.onCreate()}.     *     * @throws SQLiteException if the database cannot be opened     * @return a database object valid until {@link #getWritableDatabase}     *     or {@link #close} is called.     */    public SQLiteDatabase getReadableDatabase() {        synchronized (this) {            return getDatabaseLocked(false);        }    }    private SQLiteDatabase getDatabaseLocked(boolean writable) {        if (mDatabase != null) {            if (!mDatabase.isOpen()) {                // Darn!  The user closed the database by calling mDatabase.close().                mDatabase = null;            } else if (!writable || !mDatabase.isReadOnly()) {                // The database is already open for business.                return mDatabase;            }        }        if (mIsInitializing) {            throw new IllegalStateException("getDatabase called recursively");        }        SQLiteDatabase db = mDatabase;        try {            mIsInitializing = true;            if (db != null) {                if (writable && db.isReadOnly()) {                    db.reopenReadWrite();                }            } else if (mName == null) {                db = SQLiteDatabase.create(null);            } else {                try {                    if (DEBUG_STRICT_READONLY && !writable) {                        final String path = mContext.getDatabasePath(mName).getPath();                        db = SQLiteDatabase.openDatabase(path, mFactory,                                SQLiteDatabase.OPEN_READONLY, mErrorHandler);                    } else {                        db = mContext.openOrCreateDatabase(mName, mEnableWriteAheadLogging ?                                Context.MODE_ENABLE_WRITE_AHEAD_LOGGING : 0,                                mFactory, mErrorHandler);                    }                } catch (SQLiteException ex) {                    if (writable) {                        throw ex;                    }                    Log.e(TAG, "Couldn't open " + mName                            + " for writing (will try read-only):", ex);                    final String path = mContext.getDatabasePath(mName).getPath();                    db = SQLiteDatabase.openDatabase(path, mFactory,                            SQLiteDatabase.OPEN_READONLY, mErrorHandler);                }            }            onConfigure(db);            final int version = db.getVersion();            if (version != mNewVersion) {                if (db.isReadOnly()) {                    throw new SQLiteException("Can't upgrade read-only database from version " +                            db.getVersion() + " to " + mNewVersion + ": " + mName);                }                db.beginTransaction();                try {                    if (version == 0) {                        onCreate(db);                    } else {                        if (version > mNewVersion) {                            onDowngrade(db, version, mNewVersion);                        } else {                            onUpgrade(db, version, mNewVersion);                        }                    }                    db.setVersion(mNewVersion);                    db.setTransactionSuccessful();                } finally {                    db.endTransaction();                }            }            onOpen(db);            if (db.isReadOnly()) {                Log.w(TAG, "Opened " + mName + " in read-only mode");            }            mDatabase = db;            return db;        } finally {            mIsInitializing = false;            if (db != null && db != mDatabase) {                db.close();            }        }    }