java 从数据库生成表的实体类（PostgreSQL版）

前面写了生成表的实体类的MySQL数据库版，这里再贴上PostgreSQL数据库版。

注：pgsql字段类型所对应的Java类型只写了常见的部分类型，如有需要请自行修改完善sqlType2JavaType方法。

package generator;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
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.sql.SQLException;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

 /**
  * 从数据库生成表的实体类 
  * PostgreSQL版
  */
public class PgSQlGenerateEntityUtil {
	
	public static void main(String[] args) {
    	PgSQlGenerateEntityUtil pgGen = new PgSQlGenerateEntityUtil();
    	//PgSQlGenerateEntityUtil.basePath=""; //指定生成的位置,默认是当前工程
    	//pgGen.needEntityHelper=true;
    	//生成的包名
    	PgSQlGenerateEntityUtil.packageOutPath = "net.hlinfo.entity";
    	pgGen.generate();
       System.out.println("generate Entity to classes successful!");
        
    }
	
     //表名
    private String tableName;
    //表注释
    private String tableComment;
     //列名数组
    private String[] colNames;
     //列名类型数组
    private String[] colTypes; 
    //列名大小数组
    private int[] colSizes; 
    //列名注释
    private Map colNamesComment = new HashMap(); 
     //是否需要导入包java.util.*
    private boolean needUtil = false;
     //是否需要导入包java.sql.*
    private boolean needSql = false; 
    //是否需要导入包java.math.BigDecimal
    private boolean needBigDecimal = false; 
     //是否创建EntityHelper
    private boolean needEntityHelper = false;
    private static final SimpleDateFormat SDF = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
     
    // 数据库配置信息
    private static final String JDBC_URL = "jdbc:postgresql://127.0.0.1:5432/test";
    public static final String jdbc_user = "postgres";
    public static final String jdbc_pwd = "123456";
    private static final String DRIVER = "org.postgresql.Driver";
    
    //指定实体生成所在包的路径
    private static String basePath = new File("").getAbsolutePath();
    //指定包名
    private static String packageOutPath = "com.cy.entity";
    //作者名字
    private static final String authorName = "呐喊";
    //指定需要生成的表的表名，全部生成设置为null
    private String[] generateTables = null;
     //主键
    private static String pk;

    private PgSQlGenerateEntityUtil() {
    }
    /**
      * 功能：查询表信息的sql
     * @param tableName
     * @return comment 表的注释，type字段类型，name字段名字，notnull是否为空
     */
    private static String SQL(String tableName) {
    	if(tableName==null || "".equals(tableName)) {return null;}
    	String sql = "SELECT col_description(a.attrelid,a.attnum) as comment,"
        		+ "format_type(a.atttypid,a.atttypmod) as type,a.attname as name, a.attnotnull as notnull,a.atttypmod-4 as fields_length "
        		+ "FROM pg_class as c,pg_attribute as a where c.relname = '"+tableName+"' "
        		+ "and a.attrelid = c.oid and a.attnum>0";
    	return sql;
    	
    }
    /**
      * 功能：获取主键的sql
     * @param tableName
     * @return pk_name:主键名  | colname：主键对应字段名 | typename:主键类型
     */
    private static String PK_SQL(String tableName) {
    	if(tableName==null || "".equals(tableName)) {return null;}
    	String pksql = "select pg_constraint.conname as pk_name,pg_attribute.attname as colname,pg_type.typname as typename from pg_constraint  inner join pg_class on pg_constraint.conrelid = pg_class.oid inner join pg_attribute on pg_attribute.attrelid = pg_class.oid and  pg_attribute.attnum = pg_constraint.conkey[1] inner join pg_type on pg_type.oid = pg_attribute.atttypid where pg_class.relname = '"+tableName+"' and pg_constraint.contype='p'";
    	return pksql;
    }
    /**
     * 功能：解析字段数据，生成实体类的所有内容
     * @return
     */
    private String parse() {
        StringBuffer sb = new StringBuffer();
        sb.append("package " + packageOutPath + ";\r\n");
        sb.append("\r\n");
        // 判断是否导入工具包
        if (needUtil) {
            sb.append("import java.util.Date;\r\n");
         }
        if (needSql) {
            sb.append("import java.sql.*;\r\n");
         }
         
       for (int i = 0; i < colNames.length; i++) {
    	   String hasbd = sqlType2JavaType(colTypes[i]);
    	   if(hasbd =="BigDecimal" || "BigDecimal".equals(hasbd)) {needBigDecimal=true;}
        }
       if(needBigDecimal) {
    	   sb.append("import java.math.BigDecimal;\r\n");
        }
         // 注释部分
        sb.append("/**\r\n");
        sb.append(" * 
\r\n");
        sb.append(" * 
table name:  " + tableName + "
\r\n");
        sb.append(" * 
table comment:  " + (tableComment==null?"":tableComment) + "
\r\n");
        sb.append(" * 
author name: " + authorName + "
\r\n");
        sb.append(" * 
create time: " + SDF.format(new Date()) + "
\r\n");
        sb.append(" * 
\r\n");
        sb.append(" */ \r\n");
         // 实体部分
        String classExtends = "";
        if(needEntityHelper) {
        	classExtends=" extends EntityHelper";
          }
        sb.append("public class " + under2camel(tableName, true) + classExtends + "{\r\n\r\n");
         //实体属性
        processAllAttrs(sb);
        sb.append("\r\n");
         // 构造函数
        processConstructor(sb);//
        //get set方法
        processAllMethod(sb);
        processToString(sb);
        if(needEntityHelper) {
        	 processEntityHelper(sb,pk);
          }
        sb.append("}\r\n");
        return sb.toString();
    }
 
    /**
     * @param sb
     * @description 生成所有成员变量及注释
     */
    private void processAllAttrs(StringBuffer sb) {
        for (int i = 0; i < colNames.length; i++) {
        	if(colNamesComment.get(colNames[i])!=null &&!"".equals(colNamesComment.get(colNames[i]))) {
        		sb.append("\t/*"+colNamesComment.get(colNames[i])+"*/\r\n");
        	}
          sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colNames[i] + ";\r\n");
        }
    }
    /**
     * EntityHelper
     * @param sb
     * @param pk
     */
   private void processEntityHelper(StringBuffer sb,String pk) {
	   sb.append("\t@Override\r\n");
	   sb.append("\tpublic String getPrimaryKey() {\r\n");
	   sb.append("\t\treturn \""+pk+"\";\r\n");
	   sb.append("\t}\r\n");
   }
    /**
     * 重写toString()方法
     * @param sb
     */
    private void processToString(StringBuffer sb) {
        sb.append("\t@Override\r\n\tpublic String toString() {\r\n");
        sb.append("\t\treturn \"" +tableName + "[\" + \r\n");
        for (int i = 0; i < colNames.length; i++) {
            if (i != 0)
                sb.append("\t\t\t\", ");
            if (i == 0)
                sb.append("\t\t\t\"");
            sb.append(colNames[i] + "=\" + "
                    + colNames[i]).append(" + \r\n");
            if (i == colNames.length - 1) {
                sb.append("\t\t\t\"]\";\r\n");
            }
        }
        sb.append("\t}\r\n");
    }
    /**
     * 构造函数
     * @param sb
     */
    private void processConstructor(StringBuffer sb) {
    	 StringBuffer p = new StringBuffer();
    	 StringBuffer v = new StringBuffer();
    	 for(int i = 0; i < colNames.length; i++) {
    		 p.append(sqlType2JavaType(colTypes[i])+" "+colNames[i]);
    		 if(i!=colNames.length-1) {
    			 p.append(",");
    		 }
    		 v.append("\t\tthis."+colNames[i]+"="+colNames[i]+";\r\n");
    	 }
    	 //无参数构造函数
        sb.append("\tpublic "+under2camel(tableName,true)+"() {\r\n");
        sb.append("\t\tsuper();\r\n");
        sb.append("\t}\r\n");
         //带参构造函数
        sb.append("\tpublic "+under2camel(tableName,true)+"("+p.toString()+") {\r\n");
        sb.append(v.toString());
        sb.append("\t}\r\n");
    }
 
    /**
     * @param sb
     * @description 生成所有get/set方法
     */
    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");
        }
    }
 
    /**
      * 功能：将传入字符串的首字母转成大写
     * @param str 传入字符串
     * @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);
    }
 
    /**
      * 功能：下划线命名转驼峰命名
     * @param s
     * @param fistCharToUpperCase 首字母是否大写
     * @author 呐喊
     * @return
     */
    private String under2camel(String s,boolean fistCharToUpperCase) {
       String separator = "_";
    	String under="";
    	s = s.toLowerCase().replace(separator, " ");
    	String sarr[]=s.split(" ");
    	for(int i=0;i0) {
    		sqlType = sqlType.substring(0, sqlType.indexOf("("));
    	}
    	String returnType=null;
    	switch (sqlType) {
			case "boolean":
			case "bit":
				returnType =  "boolean";
				break;
			case "bytea":
				returnType =  "byte";
				break;
			case "bigint":
			case "int8":
			case "bigserial":
				returnType =  "Long";
				break;
			case "integer":
			case "int2":
			case "int4":
			case "smallint":
			case "serial":
				returnType =  "Integer";
				break;
			case "real":
			case "double precision":
				returnType =  "double";
				break;
			case "text":
			case "character varying":
			case "character":
			case "varchar":
			case "char":
			case "uuid":
			case "json":
			case "xml":
			case "money":
			case "timestamp without time zone":
			case "timestamp with time zone":
			case "time without time zone":
			case "time with time zone":
				returnType =  "String";
				break;
			case "inet":
			case "cidr":
			case "macaddr":
			case "macaddr8":
			case "box":
			case "circle":
			case "interval":
			case "line":
			case "lseg":
			case "path":
			case "point":
			case "polygon":
			case "varbit":
				returnType =  "Object";
				break;
			case "numeric":
			case "decimal":
				returnType =  "BigDecimal";
				break;
			default:
				break;
		 }
        return returnType;
    }
    /**
      * 功能：获取并创建实体所在的路径目录
     * @return
     */
    private static String pkgDirName() {
       String dirName = basePath + "/src/" + packageOutPath.replace(".", "/");
       File dir = new File(dirName);
       if (!dir.exists()) {dir.mkdirs();System.out.println("mkdirs dir 【" + dirName + "】");}
       return dirName;
    }
    /**
     * 功能：生成EntityHelper
     */
    private void EntityHelper() {
    	String dirName = PgSQlGenerateEntityUtil.pkgDirName();
    	String javaPath = dirName + "/EntityHelper.java";
       try {
    	   StringBuffer sb = new StringBuffer();
          sb.append("package " + packageOutPath + ";\r\n");
          sb.append("\r\n");
          sb.append("public abstract class EntityHelper{\r\n\r\n");
          sb.append("\tpublic abstract String getPrimaryKey();\r\n");
          sb.append("\r\n");
          sb.append("}\r\n");
			FileWriter fw = new FileWriter(javaPath);
			PrintWriter pw = new PrintWriter(fw);
			pw.println(sb.toString());
          pw.flush();
          if (pw != null){pw.close();}
          System.out.println("create class 【EntityHelper】");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
    }
    /**
     * 功能： 生成实体类的主方法
     */
    private void generate(){
    	Connection conn=null;
      try {
			//数据库的连接
			PreparedStatement pStemt = null;
			Class.forName(DRIVER);
			conn = DriverManager.getConnection(JDBC_URL, jdbc_user, jdbc_pwd);
			if(conn!=null) {
				System.out.println("connect database success..."+conn);
			}else {
				System.out.println("connect database failed^_^");
				return;
			}
			//获取数据库的元数据
			DatabaseMetaData db = conn.getMetaData();
			//是否有指定生成表，有指定则直接用指定表，没有则全表生成
			List tableNames = new ArrayList<>();
			List tableComments = new ArrayList<>();
			if (generateTables == null) {
			    //从元数据中获取到所有的表名
			    ResultSet rs = db.getTables(null, null, null, new String[] { "TABLE" });
			    while (rs.next()) { 
			    	tableNames.add(rs.getString(3));//表名
			    	tableComments.add(rs.getString(5));//表注释
			      }
			} else {
			    for (String tableName : generateTables) tableNames.add(tableName);
			}
			if(needEntityHelper) {
				EntityHelper();
			}
			String tableSql;
			PrintWriter out = null;
			for (int j = 0; j < tableNames.size(); j++) {
			    tableName = tableNames.get(j);
			    tableComment = tableComments.get(j);
			    tableSql = SQL(tableName);
			    pStemt = conn.prepareStatement(tableSql,ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
			    ResultSet rstb = pStemt.executeQuery();
			    rstb.last();
			    int rowCount = rstb.getRow();
			    rstb.beforeFirst();
			    colNames = new String[rowCount];
			    colTypes = new String[rowCount];
			    colSizes = new int[rowCount];
			    int idx = 0;
			    while(rstb.next()) {
			        	colNames[idx] = rstb.getString("name");
			        	colTypes[idx] = rstb.getString("type");
			        	colSizes[idx] = rstb.getInt("fields_length");
			        	colNamesComment.put(rstb.getString("name"), rstb.getString("comment"));
			        	idx++;
			      }
			      //获取主键
			    pStemt = conn.prepareStatement(PK_SQL(tableName));
			    ResultSet rspk = pStemt.executeQuery();
			    while(rspk.next()) {
			    pk=rspk.getString("colname");
			      }
			      //解析生成实体java文件的所有内容
			    String content = parse();
			      //输出生成文件
			    String dirName = PgSQlGenerateEntityUtil.pkgDirName();
			    String javaPath = dirName + "/" + under2camel(tableName, true) + ".java";
			    FileWriter fw = new FileWriter(javaPath);
			    out = new PrintWriter(fw);
			    out.println(content);
			    out.flush();
			    System.out.println("create class 【" + tableName + "】");
			}
			if (out != null) {
				out.close();
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			if(conn!=null) {
				try {
					conn.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
    }
 
    
}