JDBC框架

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public class JdbcUtils {
// 表示定义数据库的用户名
private final String USERNAME = "root";
// 定义数据库的密码
private final String PASSWORD = "admin";
// 定义数据库的驱动信息
private final String DRIVER = "com.mysql.jdbc.Driver";
// 定义访问数据库的地址
private final String URL = "jdbc:mysql://localhost:3306/testdb";
// 定义数据库的链接
private Connection connection;
// 定义sql语句的执行对象
private PreparedStatement pstmt;
// 定义查询返回的结果集合
private ResultSet resultSet;
// 实现批处理操作的功能
private Statement stmt;
public JdbcUtils() {
try {
Class.forName(DRIVER);
System.out.println("注册驱动成功!!");
} catch (Exception e) {
// TODO: handle exception
}
}
// 定义获得数据库的链接
public Connection getConnection() {
try {
connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
} catch (Exception e) {
// TODO: handle exception
}
return connection;
}
public boolean deleteByBatch(String[] sql) throws SQLException{
boolean flag = false;
stmt = connection.createStatement();
if(sql!=null){
for(int i=0;i<sql.length;i++){
stmt.addBatch(sql[i]);
}
}
int[] count = stmt.executeBatch();
if(count!=null){
flag = true;
}
return flag;
}
/**
* 完成对数据库的表的添加删除和修改的操作
*
* @param sql
* @param params
* @return
* @throws SQLException
*/
public boolean updateByPreparedStatement(String sql, List<Object> params)
throws SQLException {
boolean flag = false;
int result = -1;// 表示当用户执行添加删除和修改的时候所影响数据库的行数
pstmt = connection.prepareStatement(sql);
int index = 1;
if (params != null && !params.isEmpty()) {
for (int i = 0; i < params.size(); i++) {
pstmt.setObject(index++, params.get(i));
}
}
result = pstmt.executeUpdate();
flag = result > 0 ? true : false;
return flag;
}
/**
* 查询返回单条记录
*
* @param sql
* @param params
* @return
* @throws SQLException
*/
public Map<String, Object> findSimpleResult(String sql, List<Object> params)
throws SQLException {
Map<String, Object> map = new HashMap<String, Object>();
int index = 1;
pstmt = connection.prepareStatement(sql);
if (params != null && !params.isEmpty()) {
for (int i = 0; i < params.size(); i++) {
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();// 返回查询结果
ResultSetMetaData metaData = resultSet.getMetaData();
int col_len = metaData.getColumnCount();// 获得列的名称
while (resultSet.next()) {
for (int i = 0; i < col_len; i++) {
String cols_name = metaData.getColumnName(i + 1);
Object cols_value = resultSet.getObject(cols_name);
if (cols_value == null) {
cols_value = "";
}
map.put(cols_name, cols_value);
}
}
return map;
}
/**
* 查询返回多行记录
*
* @param sql
* @param params
* @return
* @throws SQLException
*/
public List<Map<String, Object>> findMoreResult(String sql,
List<Object> params) throws SQLException {
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
int index = 1;
pstmt = connection.prepareStatement(sql);
if (params != null && !params.isEmpty()) {
for (int i = 0; i < params.size(); i++) {
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();
ResultSetMetaData metaData = resultSet.getMetaData();
int cols_len = metaData.getColumnCount();
while (resultSet.next()) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < cols_len; i++) {
String cols_name = metaData.getColumnName(i + 1);
Object cols_value = resultSet.getObject(cols_name);
if (cols_value == null) {
cols_value = "";
}
map.put(cols_name, cols_value);
}
list.add(map);
}
return list;
}
// jdbc的封装可以用反射机制来封装：
public <T> T findSimpleRefResult(String sql, List<Object> params,
Class<T> cls) throws Exception {
T resultObject = null;
int index = 1;
pstmt = connection.prepareStatement(sql);
if (params != null && !params.isEmpty()) {
for (int i = 0; i < params.size(); i++) {
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();
ResultSetMetaData metaData = resultSet.getMetaData();
int cols_len = metaData.getColumnCount();
while (resultSet.next()) {
// 通过反射机制创建实例
resultObject = cls.newInstance();
for (int i = 0; i < cols_len; i++) {
String cols_name = metaData.getColumnName(i + 1);
Object cols_value = resultSet.getObject(cols_name);
if (cols_value == null) {
cols_value = "";
}
Field field = cls.getDeclaredField(cols_name);
field.setAccessible(true);// 打开javabean的访问private权限
field.set(resultObject, cols_value);
}
}
return resultObject;
}
/**
* 通过反射机制访问数据库
*
* @param <T>
* @param sql
* @param params
* @param cls
* @return
* @throws Exception
*/
public <T> List<T> findMoreRefResult(String sql, List<Object> params,
Class<T> cls) throws Exception {
List<T> list = new ArrayList<T>();
int index = 1;
pstmt = connection.prepareStatement(sql);
if (params != null && !params.isEmpty()) {
for (int i = 0; i < params.size(); i++) {
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();
ResultSetMetaData metaData = resultSet.getMetaData();
int cols_len = metaData.getColumnCount();
while (resultSet.next()) {
T resultObject = cls.newInstance();
for (int i = 0; i < cols_len; i++) {
String cols_name = metaData.getColumnName(i + 1);
Object cols_value = resultSet.getObject(cols_name);
if (cols_value == null) {
cols_value = "";
}
Field field = cls.getDeclaredField(cols_name);
field.setAccessible(true);
field.set(resultObject, cols_value);
}
list.add(resultObject);
}
return list;
}
public void releaseConn() {
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (pstmt != null) {
try {
pstmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

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