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? 今天突然想起之前從astah-professional專門畫ER圖的工具 的一個Sample中取得Java代碼，相當棒的一段代碼，只需要通過JDBC連接就可以得到數據庫信息，主要是通過 java.sql.DatabaseMetaData 這個類實現。先記錄下來分享一下！

1. ?db.properties

driver=org.postgresql.Driver? url=jdbc:postgresql://12.3.3.3:5432/test username=1 password=3

2. 核心類JdbcUtils

public?class?JdbcUtils?{Properties?ps;boolean?isInitialized;protected?String?driver;protected?String?url;protected?String?username;protected?String?password;protected?ConnectionInfo?connInfo;public?static?void?main(String[]?args)?throws?Exception?{JdbcUtils?j1?=?new?JdbcUtils();j1.process();}/***?*/public?JdbcUtils()?{try?{this.init();}?catch?(IOException?e)?{?e.printStackTrace();}}protected?void?init()?throws?IOException?{if(isInitialized)?{return;}ps?=?new?Properties();ps.load(JdbcUtils.class.getResourceAsStream("db.properties"));driver?=?ps.getProperty("driver");url?=?ps.getProperty("url");username?=?ps.getProperty("username");password?=?ps.getProperty("password");this.connInfo?=?new?ConnectionInfo(this.url);isInitialized?=?true;System.out.println("Load?configurations.");}/***?*?*?@param?executor*?@throws?Exception*/public?void?process()?throws?Exception?{Connection?conn?=?getConnection();System.out.println("Has?connected....");ResultSet?rs?=?null;String?tableName?=?"product";?try?{DatabaseMetaData?meta?=?conn.getMetaData();?//打印?引入該?表的所有外鍵try?{?System.out.println("-------?Print?all?foreigh?key?from?table?'"?+?tableName?+?"'?--------");System.out.println("Seq Table Column(FK)");rs?=?meta.getExportedKeys(conn.getCatalog(),?null,?tableName);while?(rs.next())?{String?fkTableName?=?rs.getString("FKTABLE_NAME");String?fkColumnName?=?rs.getString("FKCOLUMN_NAME");int?fkSequence?=?rs.getInt("KEY_SEQ");System.out.println(String.format("%d %s %s",?fkSequence,?fkTableName,?fkColumnName));}System.out.println("");}?finally?{closeResultSet(rs);}try?{//打印該庫的所有表System.out.println("-------?Print?all?table?name?in?this?database?'"?+?this.connInfo.db?+?"'------");String[]?types?=?{"TABLE"};rs?=?meta.getTables(null,?null,?"%",?types);?System.out.println(this.getTablesDetail("Table?list",?rs));?}?finally?{closeResultSet(rs);}?//try?{//打印?出該庫所有外鍵的Drop腳本System.out.println("-------?Print?all?table?foreign?keys?drop?scripts?in?this?database?'"?+?this.connInfo.db?+?"'------");String[]?types?=?{"TABLE"};rs?=?meta.getTables(null,?null,?"%",?types);?collectAllTableFK(rs,?meta);?}?finally?{closeResultSet(rs);}??//try?{//打印?引入該?表的所有外鍵System.out.println("-------?Print?all?tables?which?has?foreign?key?from?table?'"?+?tableName?+?"'------");rs?=?meta.getExportedKeys(conn.getCatalog(),?null,?tableName);System.out.println(this.getKeyDetail("Exported?keys",?rs));}?finally?{closeResultSet(rs);}try?{?//打印該表的所有外鍵System.out.println("-------?Print?all?tables?which?table?'"?+?tableName?+?"'?reference?to.------");rs?=?meta.getImportedKeys(conn.getCatalog(),?null,?tableName);System.out.println(this.getKeyDetail("Imported?keys",?rs));?}?finally?{closeResultSet(rs);}}?finally?{closeResultSet(rs);closeConnection(conn);}?}/***?@param?rs*/private?void?closeResultSet(ResultSet?rs)?{if(rs?!=null)?{try?{rs.close();}?catch?(SQLException?e)?{}}}/***?@param?con*/private?void?closeConnection(Connection?con)?{if(con?!=null)?{try?{con.close();}?catch?(SQLException?e)?{}}}/***?@param?tables*?@return*?@throws?SQLException*/private?String?collectAllTableFK(ResultSet?tables,?DatabaseMetaData?meta)?throws?SQLException?{Set<String>?s?=?new?HashSet<String>();StringBuilder?sb?=?new?StringBuilder();while(tables.next())?{??String?tn?=?tables.getString("TABLE_NAME");?String?scm?=?tables.getString("TABLE_SCHEM");ResultSet?fks?=?meta.getExportedKeys(meta.getConnection().getCatalog(),?null,?tn);String[]?fkns?=?this.collectFK(tn,?s,?fks,?new?Transformer()?{?public?Object?transform(Object?o)?{//table?,?fkreturn?String.format("ALTER?TABLE?%s?DROP?CONSTRAINT?%s;\n",?Array.get(o,?0),?Array.get(o,?1));}});if(fkns.length==0)?{continue;}String?ds?=?String.format("%s:?%s",?tn,?StringUtils.join(fkns,?"\n"));sb.append(StringUtils.join(fkns,?""));?}?System.out.println("FK---------------\n"?+?sb.toString());return?sb.toString();}private?String[]?collectFK(String?table,?Set<String>?fks,?ResultSet?ekRS,?Transformer?transformer)?throws?SQLException?{Set<String>?s?=?new?HashSet<String>();while(ekRS.next())?{String?fktn?=?ekRS.getString("FKTABLE_NAME");String?v?=?ekRS.getString("FK_NAME");s.add((String)transformer.transform(new?String[]?{fktn,?v}));}ekRS.close();return??s.toArray(new?String[s.size()]);}private?String?getTablesDetail(String?head,?ResultSet?rs)?throws?SQLException?{return?this.getKeyDetail(head,?rs,?getTablesRsFields());}private?String?getKeyDetail(String?head,?ResultSet?rs)?throws?SQLException?{return?this.getKeyDetail(head,?rs,?getKeysRsColumns());}private?String?getKeyDetail(String?head,?ResultSet?rs,?String[]?cols)?throws?SQLException?{StringBuilder?sb?=?new?StringBuilder();sb.append("--------"?+?head?+?"----------\n");while?(rs.next())?{?sb.append("#\n");for?(String?s?:?cols)?{try?{sb.append(s).append("=").append(rs.getString(s)).append("\n");}catch(Exception?e)?{System.out.println("miss?field:"?+?s);}}}?sb.append("--------\n");return?sb.toString();}private?String[]?getTablesRsFields()?{return?new?String[]?{"TABLE_CAT","TABLE_SCHEM","TABLE_NAME","TABLE_TYPE","REMARKS" // "TYPE_CAT", // "TYPE_SCHEM", // "TYPE_NAME", // "SELF_REFERENCING_COL_NAME", // "REF_GENERATION"};}private?String[]?getKeysRsColumns()?{return?new?String[]?{"PKTABLE_CAT","PKTABLE_SCHEM","PKTABLE_NAME","PKCOLUMN_NAME","FKTABLE_CAT","FKTABLE_SCHEM","FKTABLE_NAME","FKCOLUMN_NAME","KEY_SEQ","UPDATE_RULE","DELETE_RULE","FK_NAME","PK_NAME","DEFERRABILITY"};}/***?@return*?@throws?Exception*/protected?Connection?getConnection()?throws?Exception?{Class.forName(driver);Connection?conn?=?DriverManager.getConnection(url,?username,?password);return?conn;}private?static?class?ConnectionInfo?{String?port?;String?ip?;String?protocol?;String?db?;?String?dbtype?;?/***?*/public?ConnectionInfo(String?url?)?{Pattern?p?=?Pattern.compile("^(.*):(.*)://(.*):(.*)/(.*)$");Matcher?m?=?p.matcher(url);if(m.find())?{protocol?=?m.group(1);dbtype?=?m.group(2);ip?=?m.group(3);port?=?m.group(4);db?=?m.group(5);}}?}?}

轉載于:https://my.oschina.net/frankies/blog/349543

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