java--生成实体类方法
2024-10-21 09:36:40
由于工作中使用eclipse开发，没有安装hibernate插件，所以无法使用自动生成实体类的功能，为了方便在网上找了段别人写的自动生成实体类方法，稍加修改，直接运行就可以生成对应表的实体类。
注意使用时方法中的数据库地址、用户名、密码要改下，还有要记得录入想要生成实体类的表明，private String tablename = "ad_campaign";
方法如下：
package com.test; import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSetMetaData;
import java.sql.SQLException; public class CreateBean {
private String tablename = "ad_campaign"; 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.* private String url = "jdbc:mysql://localhost:3306/haierdb";
private String user = "permitdbuser";
private String pwd = "permitdbpwd"; public Connection getConnection() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url, user, pwd);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
} public void createBeanMethod() {
Connection conn = getConnection(); // 得到数据库连接
//myDB为数据库名
String strsql = "select * from " + tablename;
PreparedStatement pstmt = null;
ResultSetMetaData rsmd = null;
try {
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);
}
String content = parse(colnames, colTypes, colSizes);
try {
FileWriter fw = new FileWriter(initcap(tablename) + ".java");
PrintWriter pw = new PrintWriter(fw);
pw.println(content);
pw.flush();
pw.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
pstmt.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
} /**
* 解析处理(生成实体类主体代码)
*/
private String parse(String[] colNames, String[] colTypes, int[] colSizes) {
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");
System.out.println(sb.toString());
return sb.toString(); } /**
* 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")) {
return "Date";
} else if (sqlType.equalsIgnoreCase("image")) {
return "Blob";
} else if (sqlType.equalsIgnoreCase("text")) {
return "Clob";
}
return null;
} public static void main(String[] args) {
CreateBean createBean = new CreateBean();
createBean.createBeanMethod();
}
}
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