数据库字段 到类 java bean_将数据库中表的字段自动转换为javaBean实体类

具体代码如下：

package param;

import java.io.File;

import java.io.FileWriter;

import java.io.IOException;

import java.sql.Connection;

import java.sql.DatabaseMetaData;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.util.ArrayList;

import java.util.List;

public class AutoCreateBean {

// mysql 驱动类

private static final String DRIVER = "com.mysql.jdbc.Driver";

// 数据库登录用户名

private static final String USER = "root";

// 数据库登录密码

private static final String PASSWORD = "123456";

// 数据库连接地址

private static final String URL = "jdbc:mysql://localhost:3306/ssm";

private static String tablename;

private String[] colnames; // 列名数组

private String[] colTypes; // 列名类型数组

private int[] colSizes; // 列名大小数组

private boolean f_util = false; // 是否需要导入包java.util.*

private boolean f_sql = false; // 是否需要导入包java.sql.*

/**

* 获取指定数据库中包含的表 TBlist

*

* @packageName com.util

* @return 返回所有表名(将表名放到一个集合中)

* @throws Exception

*/

public List TBlist() throws Exception {

// 访问数据库 采用 JDBC方式

Class.forName(DRIVER);

Connection con = DriverManager.getConnection(URL, USER, PASSWORD);

DatabaseMetaData md = con.getMetaData();

List list = null;

ResultSet rs = md.getTables(null, null, null, null);

if (rs != null) {

list = new ArrayList();

}

while (rs.next()) {

/*

* 设置表名

*/

String tableName = rs.getString("TABLE_NAME");

list.add(tableName);

}

rs = null;

md = null;

con = null;

return list;

}

public void GenEntity(List TBlist, String packageName)throws Exception {

Connection conn = null;

PreparedStatement pstmt = null;

ResultSetMetaData rsmd = null;

// 访问数据库 采用 JDBC方式

Class.forName(DRIVER);

conn = DriverManager.getConnection(URL, USER, PASSWORD);

for (int k = 0; k < TBlist.size(); k++) {

tablename = TBlist.get(k);

String strsql = "select * from " + tablename;

pstmt = conn.prepareStatement(strsql);

rsmd = pstmt.getMetaData();

int size = rsmd.getColumnCount();

// 共有多少列

colnames = new String[size];

colTypes = new String[size];

colSizes = new int[size];

for (int i = 0; i < rsmd.getColumnCount(); i++) {

colnames[i] = rsmd.getColumnName(i + 1);

colTypes[i] = rsmd.getColumnTypeName(i + 1);

if (colTypes[i].equalsIgnoreCase("datetime")) {

f_util = true;

}

if (colTypes[i].equalsIgnoreCase("image")

|| colTypes[i].equalsIgnoreCase("text")) {

f_sql = true;

}

colSizes[i] = rsmd.getColumnDisplaySize(i + 1);

}

markerBean(initcap(tablename), parse(), packageName);

}

pstmt = null;

rsmd = null;

conn = null;

}

/**

* 解析处理(生成实体类主体代码)

*/

private String parse() {

StringBuffer sb = new StringBuffer();

if (f_util) {

sb.append("import java.util.Date;\r\n");

}

if (f_sql) {

sb.append("import java.sql.*;\r\n\r\n\r\n");

}

sb.append("public class " + initcap(tablename) + " {\r\n");

processAllAttrs(sb);

processAllMethod(sb);

sb.append("}\r\n");

return sb.toString();

}

/**

* 创建java 文件 将生成的属性 get/set 方法 保存到 文件中 markerBean

*

* @packageName fanshe

* @param className

* 类名称

* @param content

* 类内容 包括属性 getset 方法

*/

public void markerBean(String className, String content, String packageName) {

String folder = System.getProperty("user.dir") + "/src/" + packageName + "/";

File file = new File(folder);

if (!file.exists()) {

file.mkdirs();

}

String fileName = folder + className + ".java";

try {

File newdao = new File(fileName);

FileWriter fw = new FileWriter(newdao);

fw.write("package\t" + packageName.replace("/", ".") + ";\r\n");

fw.write(content);

fw.flush();

fw.close();

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 生成所有的方法

*

* @param sb

*/

private void processAllMethod(StringBuffer sb) {

for (int i = 0; i < colnames.length; i++) {

sb.append("\tpublic void set" + initcap(colnames[i]) + "("

+ sqlType2JavaType(colTypes[i]) + " " + colnames[i]

+ "){\r\n");

sb.append("\t\tthis." + colnames[i] + " = " + colnames[i] + ";\r\n");

sb.append("\t}\r\n");

sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get"

+ initcap(colnames[i]) + "(){\r\n");

sb.append("\t\treturn " + colnames[i] + ";\r\n");

sb.append("\t}\r\n");

}

}

/**

* 解析输出属性

*

* @return

*/

private void processAllAttrs(StringBuffer sb) {

for (int i = 0; i < colnames.length; i++) {

sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + ";\r\n");

}

}

/**

* 把输入字符串的首字母改成大写

*

* @param str

* @return

*/

private String initcap(String str) {

char[] ch = str.toCharArray();

if (ch[0] >= 'a' && ch[0] <= 'z') {

ch[0] = (char) (ch[0] - 32);

}

return new String(ch);

}

private String sqlType2JavaType(String sqlType) {

if (sqlType.equalsIgnoreCase("bit")) {

return "bool";

} else if (sqlType.equalsIgnoreCase("tinyint")) {

return "byte";

} else if (sqlType.equalsIgnoreCase("smallint")) {

return "short";

} else if (sqlType.equalsIgnoreCase("int")) {

return "int";

} else if (sqlType.equalsIgnoreCase("bigint")) {

return "long";

} else if (sqlType.equalsIgnoreCase("float")) {

return "float";

} else if (sqlType.equalsIgnoreCase("decimal")

|| sqlType.equalsIgnoreCase("numeric")

|| sqlType.equalsIgnoreCase("real")) {

return "double";

} else if (sqlType.equalsIgnoreCase("money")

|| sqlType.equalsIgnoreCase("smallmoney")) {

return "double";

} else if (sqlType.equalsIgnoreCase("varchar")

|| sqlType.equalsIgnoreCase("char")

|| sqlType.equalsIgnoreCase("nvarchar")

|| sqlType.equalsIgnoreCase("nchar")) {

return "String";

} else if (sqlType.equalsIgnoreCase("datetime")

||sqlType.equalsIgnoreCase("date")){

return "Date";

}

else if (sqlType.equalsIgnoreCase("image")) {

return "Blob";

} else if (sqlType.equalsIgnoreCase("text")) {

return "Clob";

}

return null;

}

public static void main(String[] args) throws Exception {

AutoCreateBean auto = new AutoCreateBean();

List list = auto.TBlist();

auto.GenEntity(list, "bean");

System.out.println("成功!");

}

}

在此处的"bean"对应的是项目下的bean包，如下所示:

数据库里有多少张表就会创建多少张javaBean。最后结果如下：

特别在此声明，期间可能遇到错误，所以可以用下面的类来进行测试是否连接成功：

package param;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

public class ConnectToDataBase {

public static Connection getDataBaseConnection(){

String driver="com.mysql.jdbc.Driver";

String url="jdbc:mysql://localhost:3306/ssm";

String user="root";

String password="123456";

//加载驱动程序

try {

Class.forName(driver);

//System.out.println("驱动程序加载成功");

} catch (ClassNotFoundException e) {

e.printStackTrace();

}

//链接数据库

Connection conn=null;

try {

conn=DriverManager.getConnection(url, user, password);

if (!conn.isClosed()) {

System.out.println("连接数据库成功");

}

} catch (SQLException e) {

System.out.println("链接数据库失败: "+e.getMessage());

}

return conn;

}

public static void main(String[] args) {

getDataBaseConnection();

}

}