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    Android SQLite数据库增删改查操作的案例分析

    2018-04-06 10:40:45 次阅读 稿源:互联网
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    Person实体类
    代码如下:

    package com.ljq.domain;

    public class Person {
        private Integer id;
        private String name;
        private String phone;

        public Person() {
            super();
        }

        public Person(String name, String phone) {
            super();
            this.name = name;
            this.phone = phone;
        }

        public Person(Integer id, String name, String phone) {
            super();
            this.id = id;
            this.name = name;
            this.phone = phone;
        }

        public Integer getId() {
            return id;
        }

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

        public String getName() {
            return name;
        }

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

        public String getPhone() {
            return phone;
        }

        public void setPhone(String phone) {
            this.phone = phone;
        }

    }

    DBOpenHelper数据库关联类
    代码如下:

    package com.ljq.db;

    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;

    public class DBOpenHelper extends SQLiteOpenHelper {
        // 类没有实例化,是不能用作父类构造器的参数,必须声明为静态
        private static final String DBNAME = "ljq.db";
        private static final int VERSION = 1;

        // 第三个参数CursorFactory指定在执行查询时获得一个游标实例的工厂类,
        // 设置为null,代表使用系统默认的工厂类
        public DBOpenHelper(Context context) {
            super(context, DBNAME, null, VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE PERSON (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME VARCHAR(20), PHONE VARCHAR(20))");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            // 注:生产环境上不能做删除操作
            db.execSQL("DROP TABLE IF EXISTS PERSON");
            onCreate(db);
        }
    }

    PersonService业务类
    代码如下:

    package com.ljq.db;

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

    import android.content.Context;
    import android.database.Cursor;

    import com.ljq.domain.Person;

    public class PersonService {
        private DBOpenHelper dbOpenHelper = null;

        /**
         * 构造函数
         *
         * 调用getWritableDatabase()或getReadableDatabase()方法后,会缓存SQLiteDatabase实例;
         * 因为这里是手机应用程序,一般只有一个用户访问数据库,所以建议不关闭数据库,保持连接状态。
         * getWritableDatabase(),getReadableDatabase的区别是当数据库写满时,调用前者会报错,调用后者不会,
         * 所以如果不是更新数据库的话,最好调用后者来获得数据库连接。
         *
         * 对于熟悉SQL语句的程序员最好使用exeSQL(),rawQuery(),因为比较直观明了
         *
         * @param context
         */
        public PersonService(Context context){
            dbOpenHelper = new DBOpenHelper(context);
        }

        public void save(Person person){
            dbOpenHelper.getWritableDatabase().execSQL("insert into person(name, phone) values (?, ?)",
                    new Object[]{person.getName(), person.getPhone()});
        }

        public void update(Person person){
            dbOpenHelper.getWritableDatabase().execSQL("update person set name=?, phone=? where id=?",
                    new Object[]{person.getName(), person.getPhone(), person.getId()});
        }

        public void delete(Integer... ids){
            if(ids.length>0){
                StringBuffer sb = new StringBuffer();
                for(Integer id : ids){
                    sb.append("?").append(",");
                }
                sb.deleteCharAt(sb.length() - 1);
                dbOpenHelper.getWritableDatabase().execSQL("delete from person where id in ("+sb+")", (Object[])ids);
            }
        }

        public Person find(Integer id){
            Cursor cursor = dbOpenHelper.getReadableDatabase().rawQuery("select id, name, phone from person where id=?",
                    new String[]{String.valueOf(id)});
            if(cursor.moveToNext()){
                int personid = cursor.getInt(0);
                String name = cursor.getString(1);
                String phone = cursor.getString(2);
                return new Person(personid, name, phone);
            }
            return null;
        }

        public long getCount(){
            Cursor cursor = dbOpenHelper.getReadableDatabase().query("person",
                    new String[]{"count(*)"}, null,null,null,null,null);
            if(cursor.moveToNext()){
                return cursor.getLong(0);
            }
            return 0;
        }

        /**
         * 分页
         *
         * @param startResult 偏移量,默认从0开始
         * @param maxResult 每页显示的条数
         * @return
         */
        public List<Person> getScrollData(int startResult, int maxResult){
            List<Person> persons = new ArrayList<Person>();
            //Cursor cursor = dbOpenHelper.getReadableDatabase().query("person", new String[]{"id, name, phone"},
            //        "name like ?", new String[]{"%ljq%"}, null, null, "id desc", "1,2");
            Cursor cursor = dbOpenHelper.getReadableDatabase().rawQuery("select * from person limit ?,?",
                    new String[]{String.valueOf(startResult), String.valueOf(maxResult)});
            while(cursor.moveToNext()) {
                int personid = cursor.getInt(0);
                String name = cursor.getString(1);
                String phone = cursor.getString(2);
                persons.add(new Person(personid, name, phone));
            }
            return persons;
        }

       

    }

    PersonServiceTest测试类
    代码如下:

    package com.ljq.test;

    import java.util.List;

    import com.ljq.db.PersonService;
    import com.ljq.domain.Person;

    import android.test.AndroidTestCase;
    import android.util.Log;

    public class PersonServiceTest extends AndroidTestCase{
        private final String TAG = "PersonServiceTest";

        public void testSave() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            personService.save(new Person("zhangsan1", "059188893343"));
            personService.save(new Person("zhangsan2", "059188893343"));
            personService.save(new Person("zhangsan3", "059188893343"));
            personService.save(new Person("zhangsan4", "059188893343"));
            personService.save(new Person("zhangsan5", "059188893343"));
        }

        public void testUpdate() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            Person person = personService.find(1);
            person.setName("linjiqin");
            personService.update(person);
        }

        public void testFind() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            Person person = personService.find(1);
            Log.i(TAG, person.getName());
        }

        public void testList() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            List<Person> persons = personService.getScrollData(0, 10);
            for(Person person : persons){
                Log.i(TAG, person.getId() + " : " + person.getName());
            }
        }

        public void testCount() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            Log.i(TAG, String.valueOf(personService.getCount()));
        }

        public void testDelete() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            personService.delete(1);
        }

        public void testDeleteMore() throws Exception{
            PersonService personService = new PersonService(this.getContext());
            personService.delete(new Integer[]{2, 5, 6});
        }
    }

    运行结果

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