在工作中有时候需要用到建立实体类，从数据库中读取各个表格自动的生成实体类，如果表的数量比较大的时候，这个繁琐的工作量还是比较大的，这时候可以用一个小程序自动的生成实体类。其实，就是文件的读写操作而已。
数据库这里用的是mysql5.1，所以需要导入maysql的jar包。
config.properties
class="java" name="code">url=jdbc:mysql://localhost:3306/ibatis driver=com.mysql.jdbc.Driver username=root password=root
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DBUtils.java
package utils;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
public class DBUtils {
private static Properties prop = new Properties();
static{
ClassLoader loader = DBUtils.class.getClassLoader();
InputStream in = loader.getResourceAsStream("utils/config.properties");
try {
prop.load(in);
Class.forName(prop.getProperty("driver"));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static Connection getConnection() throws Exception{
return DriverManager.getConnection(prop.getProperty("url"),prop.getProperty("username"),prop.getProperty("password"));
}
public static void close(Connection conn){
if(conn != null){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args) throws Exception{
System.out.println(getConnection());
}
}
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GenEntityTool.java
package biz;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import utils.DBUtils;
public class GenEntityTool {
private String[] colNames;//列名数组
private String[] colType;//列名类型数组
private int[] colSize;//列名大小数组
private boolean f_util = false;//是否需要导入java.util.*
private boolean f_sql = false;//是否需要导入java.sql.*
public GenEntityTool(){}
public GenEntityTool(String tabName){
Connection conn = null;
String sql = "select * from " + tabName;
try {
conn = DBUtils.getConnection();
PreparedStatement prep = conn.prepareStatement(sql);
ResultSetMetaData rsmd = prep.getMetaData();
int size = rsmd.getColumnCount();//共有多少列
colNames = new String[size];
colType = new String[size];
colSize = new int[size];
for(int i=0;i<rsmd.getColumnCount();i++){
colNames[i] = rsmd.getColumnName(i+1);
colType[i] = rsmd.getColumnTypeName(i+1);
if(colType[i].equalsIgnoreCase("date")){
f_util = true;
}
if(colType[i].equalsIgnoreCase("text") || colType[i].equalsIgnoreCase("image")){
f_sql = true;
}
colSize[i] = rsmd.getColumnDisplaySize(i+1);
}
String content = parse(tabName, colNames, colType, colSize);
FileWriter fw = new FileWriter("E:\\entity\\"+initCap(tabName)+".java");
PrintWriter pw = new PrintWriter(fw);
pw.println(content);
pw.flush();
pw.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
DBUtils.close(conn);
}
}
/*
* 解析处理，生成java实体类主体代码
*/
private String parse(String tabName,String[] colNames,String[] colType,int[] colSize){
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(tabName)+"{\r\n");
processAllAttrs(sb);
processAllMethod(sb);
sb.append("}\r\n");
return sb.toString();
}
/*
* 生成所有的方法
*/
private void processAllMethod(StringBuffer sb){
for(int i=0;i<colNames.length;i++){
sb.append("\tpublic void set"+initCap(colNames[i])+"("+sqlType2JavaType(colType[i])+" "+colNames[i]+"){\r\n");
sb.append("\t\tthis."+colNames[i]+" = "+colNames[i]+";\r\n");
sb.append("\t}\r\n");
sb.append("\tpublic "+sqlType2JavaType(colType[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(colType[i])+" "+colNames[i]+";\r\n");
}
}
/*
* 把输入字符串的首字母变成大写
*
* @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 "boolean";
} 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("double")
|| 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;
}
/*
* 读取数据库中的表名
* @return表名的String数组
*
*/
private static String[] getTabNames(){
Connection conn = null;
String sql = "show tables";
String[] tabNames = null;
try {
conn = DBUtils.getConnection();
PreparedStatement prep = conn.prepareStatement(sql);
ResultSet rs = prep.executeQuery();
rs.last();
int size = rs.getRow();
tabNames = new String[size];
rs.beforeFirst();
int i=0;
while(rs.next() && i < size){
tabNames[i]=rs.getString(1);
i++;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
DBUtils.close(conn);
}
return tabNames;
}
public static void main(String[] args){
String[] tabNames = getTabNames();
for(int i=0;i<tabNames.length;i++){
new GenEntityTool(tabNames[i]);
}
}
}
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主题代码已经贴上去了，下面来进行一次啊测试...
Test.java
package biz;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import utils.DBUtils;
public class Test {
public static void main(String[] args){
String sql = "show tables";
Connection conn = null;
try {
conn = DBUtils.getConnection();
PreparedStatement prep = conn.prepareStatement(sql);
ResultSet rs = prep.executeQuery();
while(rs.next()){
System.out.println(rs.getString(1));
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
DBUtils.close(conn);
}
}
}
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