import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.lowca.robot.Crawler;
/**
* <p>
* 通用dao类，用法和说明如下：
* </p>
* <p>
* 1.不支持事务
* </p>
* <p>
* 2.不支持连接池
* </p>
* <p>
* 3.命名方法必须严格遵守java pojo和数据库的命名规范/p>
* <p>
* 4.主键必须叫做“id”，且必须为Integer类型，其他基本类型的属性必须为其封装类型
* </p>
* <p>
* 5.不支持复杂映射
* </p>
*
* @author kong
*
*/
public class Dao {
private static final String DRIVER = "org.sqlite.JDBC";
private static final String CONNECT_URL = "jdbc:sqlite:c:/robot.db";
private static final String USERNAME = null;
private static final String PASSWORD = null;
private static final Log log = LogFactory.getLog(Crawler.class);
static {
try {
Class.forName(DRIVER);
} catch (ClassNotFoundException e) {
throw new RuntimeException("加载JDBC驱动失败:\n" + e.getMessage());
}
}
/**
* 获取连接
*
* @return
* @throws SQLException
*/
private Connection getConnection() throws SQLException {
Connection conn = null;
if (USERNAME != null && PASSWORD != null)
conn = DriverManager.getConnection(CONNECT_URL, USERNAME, USERNAME);
else
conn = DriverManager.getConnection(CONNECT_URL);
conn.setAutoCommit(false);
return conn;
}
/**
* 行集映射
*
* @param <T>
* @param clazz
* @param rs
* @return
* @throws SQLException
*/
private <T> T mapping(Class<T> clazz, ResultSet rs) throws SQLException {
T t = null;
if (rs.next()) {
try {
t = clazz.newInstance();
} catch (Exception e) {
throw new RuntimeException(e);
}
ResultSetMetaData metadata = rs.getMetaData();
int size = metadata.getColumnCount();
for (int i = 0; i < size; i++) {
String columnName = metadata.getColumnLabel(i + 1);
Object columnValue = rs.getObject(metadata
.getColumnLabel(i + 1));
if (columnValue == null)
continue;
// 给对象赋值
String propertyName = toJavaCase(columnName);
String methodName = "set"
+ propertyName.substring(0, 1).toUpperCase()
+ propertyName.substring(1);
Method[] methods = clazz.getMethods();
for (Method method : methods) {
if (methodName.equals(method.getName())) {
try {
String propertyTypeName = method
.getParameterTypes()[0].getName();
String columnTypeName = columnValue.getClass()
.getName();
if (propertyTypeName
.equalsIgnoreCase(columnTypeName))
method.invoke(t, columnValue);
else {
// 转换长整型和日期类型的不适配问题
if ("java.util.Date".equals(propertyTypeName)
&& "java.lang.Long"
.equals(columnTypeName))
method.invoke(t, new Date(
(Long) columnValue));
// 转换整型为布尔型
if ("java.lang.Boolean"
.equals(propertyTypeName)
&& "java.lang.Integer"
.equals(columnTypeName))
method.invoke(t, columnValue.toString()
.equals("0") ? false : true);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
}
}
return t;
}
/**
* 释放连接
*
* @param rs
* @param ps
* @param conn
*/
public void free(ResultSet rs, PreparedStatement ps, Connection conn) {
try {
if (rs != null)
rs.close();
} catch (Exception e) {
log.error(this, e);
} finally {
try {
if (ps != null)
ps.close();
} catch (Exception e) {
log.error(this, e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
log.error(this, e);
}
}
}
}
}
/**
* 查询方法
*
* @param <T>
* @param clazz
* @param sql
* @param values
* @return
* @throws SQLException
*/
public <T> T query(Class<T> clazz, String sql, Object[] values)
throws SQLException {
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
if (values != null) {
for (int i = 0; i < values.length; i++) {
ps.setObject(i + 1, values[i]);
}
}
ResultSet rs = ps.executeQuery();
T t = mapping(clazz, rs);
free(rs, ps, conn);
return t;
}
/**
* 查询方法（不带参数）
*
* @param <T>
* @param clazz
* @param sql
* @return
* @throws SQLException
*/
public <T> T query(Class<T> clazz, String sql) throws SQLException {
return query(clazz, sql, null);
}
/**
* 查询多个对象
*
* @param <T>
* @param clazz
* @param sql
* @param values
* @return
* @throws SQLException
*/
public <T> List<T> queryList(Class<T> clazz, String sql, Object[] values)
throws SQLException {
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
if (values != null) {
for (int i = 0; i < values.length; i++) {
ps.setObject(i + 1, values[i]);
}
}
ResultSet rs = ps.executeQuery();
List<T> list = new ArrayList<T>();
T t = null;
while ((t = mapping(clazz, rs)) != null) {
list.add(t);
}
free(rs, ps, conn);
return list;
}
/**
* 查询多个对象（不带参数）
*
* @param <T>
* @param clazz
* @param sql
* @return
* @throws SQLException
*/
public <T> List<T> queryList(Class<T> clazz, String sql)
throws SQLException {
return queryList(clazz, sql, null);
}
/**
*统计一类对象的个数
*
* @param clazz
* @return
* @throws SQLException
*/
public int count(Class<?> clazz) throws SQLException {
Connection conn = getConnection();
String tableName = toDbCase(clazz.getSimpleName());
String sql = "select count(*) from " + tableName;
PreparedStatement ps = conn.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
int num = 0;
if (rs.next())
num = rs.getInt(1);
free(rs, ps, conn);
return num;
}
/**
* 根据sql统计
*
* @param sql
* @param values
* @return
* @throws SQLException
*/
public int count(String sql, Object[] values) throws SQLException {
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
if (values != null) {
for (int i = 0; i < values.length; i++) {
ps.setObject(i + 1, values[i]);
}
}
ResultSet rs = ps.executeQuery();
int num = 0;
if (rs.next())
num = rs.getInt(1);
free(rs, ps, conn);
return num;
}
/**
* 根据sql统计（不带参数）
*
* @param sql
* @return
* @throws SQLException
*/
public int count(String sql) throws SQLException {
return count(sql, null);
}
/**
* 根据id获取
*
* @param <T>
* @param clazz
* @param id
* @return
* @throws SQLException
*/
public <T> T get(Class<T> clazz, Integer id) throws SQLException {
String tableName = toDbCase(clazz.getSimpleName());
String sql = "select * from " + tableName + " where id="
+ id.intValue();
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
T t = mapping(clazz, rs);
free(rs, ps, conn);
return t;
}
/**
* 删除对象
*
* @param clazz
* @param id
* @return
* @throws SQLException
*/
public int delete(Class<?> clazz, Integer id) throws SQLException {
String tableName = toDbCase(clazz.getSimpleName());
String sql = "delete from " + tableName + " where id=" + id.intValue();
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
int rowCount = ps.executeUpdate();
free(null, ps, conn);
return rowCount;
}
/**
* 保存对象
*
* @param object
* @throws SQLException
*/
public void save(Object object) throws SQLException {
// 通过反射提取属性和属性值
Method[] methods = object.getClass().getMethods();
Map<String, Object> kvMap = new HashMap<String, Object>();
for (Method method : methods) {
if (method.getName().startsWith("set")) {
String key = method.getName().substring(3, 4).toLowerCase()
+ method.getName().substring(4);
Method getMethod = null;
Object value = null;
try {
getMethod = object.getClass().getDeclaredMethod(
method.getName().replaceFirst("set", "get"));
value = getMethod.invoke(object);
} catch (Exception e) {
throw new RuntimeException(e);
}
kvMap.put(key, value);
}
}
// 生成sql
String tableName = toDbCase(object.getClass().getSimpleName());
Object[] values = new Object[kvMap.size()];
StringBuffer sb = new StringBuffer("INSERT INTO " + tableName + "(");
StringBuffer params = new StringBuffer();
int index = 0;
for (String key : kvMap.keySet()) {
String columnName = toDbCase(key);
sb.append(columnName + ",");
params.append("?,");
values[index] = kvMap.get(key);
index++;
}
if (sb.charAt(sb.length() - 1) == ',')
sb.delete(sb.length() - 1, sb.length());
if (params.charAt(params.length() - 1) == ',')
params.delete(params.length() - 1, params.length());
sb.append(") VALUES(").append(params).append(");");
String sql = sb.toString();
// 执行sql
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
if (values != null) {
for (int i = 0; i < values.length; i++) {
ps.setObject(i + 1, values[i]);
}
}
conn.setAutoCommit(true);
ps.execute();
conn.setAutoCommit(false);
// 获取主键
ps = conn.prepareStatement("select last_insert_rowid()");
ResultSet rs = ps.executeQuery();
Integer pk = 0;
if (rs.next())
pk = rs.getInt(1);
// 给对象赋主键的值
try {
Method method = object.getClass().getDeclaredMethod("setId",
Integer.class);
method.invoke(object, pk);
} catch (Exception e) {
throw new RuntimeException(e);
}
free(null, ps, conn);
}
/**
* 更新对象
*
* @param object
* @throws SQLException
*/
public void update(Object object) throws SQLException {
// 通过反射提取属性和属性值
Method[] methods = object.getClass().getMethods();
Map<String, Object> kvMap = new HashMap<String, Object>();
for (Method method : methods) {
if (method.getName().startsWith("set")) {
String key = method.getName().substring(3, 4).toLowerCase()
+ method.getName().substring(4);
Method getMethod = null;
Object value = null;
try {
getMethod = object.getClass().getDeclaredMethod(
method.getName().replaceFirst("set", "get"));
value = getMethod.invoke(object);
} catch (Exception e) {
throw new RuntimeException(e);
}
kvMap.put(key, value);
}
}
// 生成sql
String tableName = toDbCase(object.getClass().getSimpleName());
Object[] values = new Object[kvMap.size()];
StringBuffer sb = new StringBuffer("UPDATE " + tableName + " ");
int index = 0;
Integer id = 0;
boolean firstTime = true;
for (String key : kvMap.keySet()) {
String columnName = toDbCase(key);
if (key.equalsIgnoreCase("id")) {
id = (Integer) kvMap.get(key);
continue;
}
sb.append((firstTime ? " SET " : "") + columnName + "=?,");
firstTime = false;
values[index] = kvMap.get(key);
index++;
}
values[index] = id;
if (sb.charAt(sb.length() - 1) == ',')
sb.delete(sb.length() - 1, sb.length());
sb.append(" WHERE id=?;");
String sql = sb.toString();
// 执行sql
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
if (values != null) {
for (int i = 0; i < values.length; i++) {
ps.setObject(i + 1, values[i]);
}
}
conn.setAutoCommit(true);
ps.executeUpdate();
conn.setAutoCommit(false);
free(null, ps, conn);
}
/**
* 执行sql语句
*
* @param sql
* @param values
* @return
* @throws SQLException
*/
public boolean execute(String sql, Object[] values) throws SQLException {
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
if (values != null) {
for (int i = 0; i < values.length; i++) {
ps.setObject(i + 1, values[i]);
}
}
conn.setAutoCommit(true);
boolean r = ps.execute();
conn.setAutoCommit(false);
free(null, ps, conn);
return r;
}
/**
* 执行sql语句，不带参数
*
* @param sql
* @return
* @throws SQLException
*/
public boolean execute(String sql) throws SQLException {
return execute(sql, null);
}
/**
* 检查数据库是否有这个表
*
* @param clazz
* @return
* @throws SQLException
*/
public boolean existTable(Class<?> clazz) throws SQLException {
String tableName = toDbCase(clazz.getSimpleName());
String sql = "SELECT COUNT(*) AS table_count FROM sqlite_master WHERE TYPE='table' AND NAME=?;";
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
ps.setObject(1, tableName);
ResultSet rs = ps.executeQuery();
int num = 0;
if (rs.next()) {
num = rs.getInt("table_count");
}
free(null, ps, conn);
return num > 0 ? true : false;
}
/**
* 使用类来创建表
*
* @param clazz
* @param delIfExist
* 如果表已存在，true表示删除旧表并重新建表，false表示保留旧表不再重新建
* @throws SQLException
*/
public void createTable(Class<?> clazz, boolean delIfExist)
throws SQLException {
// 如果表已经存在，则看看是否需要删除
boolean existTable = existTable(clazz);
if (!delIfExist && existTable) {
return;
}
if (delIfExist && existTable) {
deleteTable(clazz);
}
// 通过反射提取属性和属性值
Method[] methods = clazz.getMethods();
Map<String, String> kvMap = new HashMap<String, String>();
for (Method method : methods) {
if (method.getName().startsWith("set")) {
String property = method.getName().substring(3, 4)
.toLowerCase()
+ method.getName().substring(4);
String propertyClassName = method.getParameterTypes()[0]
.getName();
kvMap.put(property, propertyClassName);
}
}
// 生成sql
String tableName = toDbCase(clazz.getName());
StringBuffer sb = new StringBuffer("CREATE TABLE " + tableName
+ " (id INTEGER PRIMARY KEY,");
for (String key : kvMap.keySet()) {
if (key.equalsIgnoreCase("id")) {
continue;
}
String columnName = toDbCase(key);
String propertyClassName = kvMap.get(key);
String dbTypeName = getDbTypeName(propertyClassName);
sb.append(columnName + " " + dbTypeName + ",");
}
if (sb.charAt(sb.length() - 1) == ',')
sb.delete(sb.length() - 1, sb.length());
sb.append(");");
String sql = sb.toString();
// 执行sql
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
conn.setAutoCommit(true);
ps.execute();
conn.setAutoCommit(false);
free(null, ps, conn);
}
/**
* 使用sql来建表
*
* @param sql
* @throws SQLException
*/
public void createTable(String sql) throws SQLException {
// 创建表
Connection conn = getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
conn.setAutoCommit(true);
ps.execute();
conn.setAutoCommit(false);
free(null, ps, conn);
}
/**
* 创建表，如果表已经存在，则不新建
*
* @param clazz
* @throws SQLException
*/
public void createTable(Class<?> clazz) throws SQLException {
createTable(clazz, false);
}
/**
* 删除表
*
* @param clazz
* @throws SQLException
*/
public void deleteTable(Class<?> clazz) throws SQLException {
String tableName = toDbCase(clazz.getSimpleName());
String sql = "DROP TABLE IF EXISTS " + tableName;
execute(sql);
}
private String getDbTypeName(String propertyClassName) {
if ("java.lang.Integer".equals(propertyClassName)
|| "java.lang.Long".equals(propertyClassName)
|| "java.lang.Character".equals(propertyClassName)
|| "java.lang.Short".equals(propertyClassName))
return "INTEGER";
if ("java.lang.Float".equals(propertyClassName)
|| "java.lang.Double".equals(propertyClassName))
return "REAL";
if ("java.util.Date".equals(propertyClassName))
return "DATETIME";
if ("java.lang.Boolean".equals(propertyClassName))
return "TINYINT";
if ("java.lang.String".equals(propertyClassName))
return "VARCHAR";
return "";
}
/**
* 数据库命名方式转换成java的命名方式
*
* @param s
* @return
*/
private static String toJavaCase(String s) {
if (s == null || s.trim().length() == 0)
return s;
StringBuffer sb = new StringBuffer();
String[] array = s.split("_");
boolean firstTime = true;
for (String e : array) {
if (e.length() == 0)
continue;
else if (e.length() == 1)
sb.append(!firstTime ? e.toUpperCase() : e);
else
sb.append(!firstTime ? (e.substring(0, 1).toUpperCase() + e
.substring(1)) : e);
firstTime = false;
}
return sb.toString();
}
/**
* Java命名方式转换成数据库的命名方式
*
* @param s
* @return
*/
private static String toDbCase(String s) {
if (s == null || s.trim().length() == 0)
return s;
char[] chars = s.toCharArray();
boolean firstTime = true;
StringBuffer sb = new StringBuffer();
for (char c : chars) {
if (c >= 'A' && c <= 'Z') {
char c1 = (char) (c + 32);
sb.append(firstTime ? c1 : "_" + c1);
} else
sb.append(c);
firstTime = false;
}
return sb.toString();
}
public static void main(String[] args) {
// System.out
// .println(toDbCase("theyBeganToHumWhenSeeingJacksonWalkIntoTheHall"));
// System.out
// .println(toJavaCase(toDbCase("theyBeganToHumWhenSeeingJacksonWalkIntoTheHall")));
StringBuffer sb = new StringBuffer("sdsdfds1");
sb.delete(sb.length() - 1, sb.length());
System.out.println(sb);
}
}
[原创]通用的面向对象查询的dao
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转载自kongcodecenter.iteye.com/blog/1137001
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