SQLite 操作封装 —— DatabaseUtil
DatabaseUtil.javaview sourceprint?001package com.dbexample;002 003import android.content.ContentValues;004import android.content.Context;005import android.database.Cursor;006import android.database.SQLException;007import android.database.sqlite.SQLiteDatabase;008import android.database.sqlite.SQLiteOpenHelper;009import android.util.Log;010 011public class DatabaseUtil{012 013 private static final String TAG = "DatabaseUtil";014 015 /**016 * Database Name017 */018 private static final String DATABASE_NAME = "student_database";019 020 /**021 * Database Version022 */023 private static final int DATABASE_VERSION = 1;024 025 /**026 * Table Name027 */028 private static final String DATABASE_TABLE = "tb_student";029 030 /**031 * Table columns032 */033 public static final String KEY_NAME = "name";034 public static final String KEY_GRADE = "grade";035 public static final String KEY_ROWID = "_id";036 037 /**038 * Database creation sql statement039 */040 private static final String CREATE_STUDENT_TABLE =041 "create table " + DATABASE_TABLE + " (" + KEY_ROWID + " integer primary key autoincrement, "042 + KEY_NAME +" text not null, " + KEY_GRADE + " text not null);";043 044 /**045 * Context046 */047 private final Context mCtx;048 049 private DatabaseHelper mDbHelper;050 private SQLiteDatabase mDb;051 052 /**053 * Inner private class. Database Helper class for creating and updating database.054 */055 private static class DatabaseHelper extends SQLiteOpenHelper {056 DatabaseHelper(Context context) {057 super(context, DATABASE_NAME, null, DATABASE_VERSION);058 }059 /**060 * onCreate method is called for the 1st time when database doesn't exists.061 */062 @Override063 public void onCreate(SQLiteDatabase db) {064 Log.i(TAG, "Creating DataBase: " + CREATE_STUDENT_TABLE);065 db.execSQL(CREATE_STUDENT_TABLE);066 }067 /**068 * onUpgrade method is called when database version changes.069 */070 @Override071 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {072 Log.w(TAG, "Upgrading database from version " + oldVersion + " to "073 + newVersion);074 }075 }076 077 /**078 * Constructor - takes the context to allow the database to be079 * opened/created080 *081 * @param ctx the Context within which to work082 */083 public DatabaseUtil(Context ctx) {084 this.mCtx = ctx;085 }086 /**087 * This method is used for creating/opening connection088 * @return instance of DatabaseUtil089 * @throws SQLException090 */091 public DatabaseUtil open() throws SQLException {092 mDbHelper = new DatabaseHelper(mCtx);093 mDb = mDbHelper.getWritableDatabase();094 return this;095 }096 /**097 * This method is used for closing the connection.098 */099 public void close() {100 mDbHelper.close();101 }102 103 /**104 * This method is used to create/insert new record Student record.105 * @param name106 * @param grade107 * @return long108 */109 public long createStudent(String name, String grade) {110 ContentValues initialValues = new ContentValues();111 initialValues.put(KEY_NAME, name);112 initialValues.put(KEY_GRADE, grade);113 return mDb.insert(DATABASE_TABLE, null, initialValues);114 }115 /**116 * This method will delete Student record.117 * @param rowId118 * @return boolean119 */120 public boolean deleteStudent(long rowId) {121 return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;122 }123 124 /**125 * This method will return Cursor holding all the Student records.126 * @return Cursor127 */128 public Cursor fetchAllStudents() {129 return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_NAME,130 KEY_GRADE}, null, null, null, null, null);131 }132 133 /**134 * This method will return Cursor holding the specific Student record.135 * @param id136 * @return Cursor137 * @throws SQLException138 */139 public Cursor fetchStudent(long id) throws SQLException {140 Cursor mCursor =141 mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,142 KEY_NAME, KEY_GRADE}, KEY_ROWID + "=" + id, null,143 null, null, null, null);144 if (mCursor != null) {145 mCursor.moveToFirst();146 }147 return mCursor;148 }149 150 /**151 * This method will update Student record.152 * @param id153 * @param name154 * @param standard155 * @return boolean156 */157 public boolean updateStudent(int id, String name, String standard) {158 ContentValues args = new ContentValues();159 args.put(KEY_NAME, name);160 args.put(KEY_GRADE, standard);161 return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + id, null) > 0;162 }163}[代码] 使用方法01//插入02DatabaseUtil dbUtil = new DatabaseUtil(this);03dbUtil.open();04dbUtil.createStudent("Prashant Thakkar", "10th");05dbUtil.close();06 07//查询08DatabaseUtil dbUtil = new DatabaseUtil(this);09dbUtil.open();10Cursor cursor = dbUtil.fetchAllStudents();11if(cursor != null){12 while(cursor.moveToNext()){13 Log.i("Student", "Student Name: " + cursor.getString(1) +14 " Grade " + cursor.getString(2));15 }16}17dbUtil.close();
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