java 生成sql java生成sql查询语句

package Main;

import javax.xml.bind.annotation.XmlElement;
import java.io.*;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.List;

public class GenerateSqlFromEntityUtil {

public static void main(String[] a) {
// 实体类的位置
Class klass = pojo.XsVNew.class;
// 生成的sql语句的位置
String outputPath = "C:/outSql/XsVNew.txt";
generateTableSql(klass, outputPath, null);
System.out.println("生成结束");
}

public static void writeFile(String content, String outputPath) {
File file = new File(outputPath);
System.out.println("文件路径: " + file.getAbsolutePath());
// 输出文件的路径
if (!file.getParentFile().exists()) {
file.getParentFile().mkdirs();
}
FileOutputStream fos = null;
OutputStreamWriter osw = null;
BufferedWriter out = null;

try {
// 如果文件存在，就删除
if (file.exists()) {
file.delete();
}
file.createNewFile();
fos = new FileOutputStream(file, true);
osw = new OutputStreamWriter(fos);
out = new BufferedWriter(osw);
out.write(content);
// 清空缓冲流，把缓冲流里的文本数据写入到目标文件里
out.flush();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}

try {
osw.close();
} catch (IOException e) {
e.printStackTrace();
}

try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

public static void generateTableSql(Class obj,
String outputPath, String tableName) {
// tableName 如果是 null，就用类名做表名
if (tableName == null || tableName.equals("")) {
tableName = obj.getName();
tableName = tableName.substring(tableName.lastIndexOf(".") + 1);
}
// 表名用大写字母
tableName = tableName.toUpperCase();

Field[] fields = obj.getDeclaredFields();
Object param ;
String column ;

StringBuilder sb = new StringBuilder();

sb.append("drop table if exists ").append(tableName).append(";\r\n");

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

sb.append("create table ").append(tableName).append("(\r\n");

System.out.println(tableName);

boolean firstId = true;

for (int i = 0; i < fields.length; i++) {
Field f = fields[i];

column = f.getName();

System.out.println(column + ", " + f.getType().getSimpleName());

param = f.getType();
sb.append(column); // 一般第一个是主键

if (param instanceof Integer) {
sb.append(" INTEGER ");
} else {
// 注意：根据需要，自行修改 varchar 的长度。这里设定为长度等于 50
int length = 50;
sb.append(" VARCHAR(" + length + ")");
}

if (firstId == true) {
sb.append(" PRIMARY KEY ");
firstId = false;
}

// 获取字段中包含 fieldMeta 的注解

// 获取属性的所有注释
Annotation[] allAnnotations = f.getAnnotations();

XmlElement xmlElement = null;
Class annotationType = null;

for (Annotation an : allAnnotations) {
sb.append(" COMMIT '");
xmlElement = (XmlElement) an;
annotationType = an.annotationType();
param = ((XmlElement) an).name();
System.out.println("属性 " + f.getName()
+ " ----- 的注释类型有: " + param);
sb.append(param).append("'");
}

if (i != fields.length - 1) { // 最后一个属性后面不加逗号
sb.append(", ");
}

sb.append("\n");
}

String sql = sb.toString();

sql = sb.substring(0, sql.length() - 1)
+ "\n) " + "ENGINE = INNODB DEFAULT CHARSET = utf8;";

writeFile(sql, outputPath);
}
}