问题
I'd like to retrieve all table names from a database schema, and, if possible, get all table starting with a specified prefix.
I tried using JDBC's connection.getMetaData().getTables() but it didn't work at all.
Connection jdbcConnection = DriverManager.getConnection("", "", "");
DatabaseMetaData m = jdbcConnection.getMetaData();
ResultSet tables = m.getTables(jdbcConnection.getCatalog(), null, "TAB_%", null);
for (int i = 0; i < tables.getMetaData().getColumnCount(); i++) {
System.out.println("table = " + tables.getMetaData().getTableName(i));
}
Could someone help me on this?
回答1:
You need to iterate over your ResultSet calling next().
This is an example from java2s.com:
DatabaseMetaData md = conn.getMetaData();
ResultSet rs = md.getTables(null, null, "%", null);
while (rs.next()) {
System.out.println(rs.getString(3));
}
Column 3 is the TABLE_NAME (see documentation of DatabaseMetaData::getTables).
回答2:
public void getDatabaseMetaData()
{
try {
DatabaseMetaData dbmd = conn.getMetaData();
String[] types = {"TABLE"};
ResultSet rs = dbmd.getTables(null, null, "%", types);
while (rs.next()) {
System.out.println(rs.getString("TABLE_NAME"));
}
}
catch (SQLException e) {
e.printStackTrace();
}
}
回答3:
In your example problem is passed table name pattern in getTables function of DatabaseMetaData.
Some database supports Uppercase identifier, some support lower case identifiers. For example oracle fetches the table name in upper case, while postgreSQL fetch it in lower case.
DatabaseMetaDeta provides a method to determine how the database stores identifiers, can be mixed case, uppercase, lowercase see:http://docs.oracle.com/javase/7/docs/api/java/sql/DatabaseMetaData.html#storesMixedCaseIdentifiers()
From below example, you can get all tables and view of providing table name pattern, if you want only tables then remove "VIEW" from TYPES array.
public class DBUtility {
private static final String[] TYPES = {"TABLE", "VIEW"};
public static void getTableMetadata(Connection jdbcConnection, String tableNamePattern, String schema, String catalog, boolean isQuoted) throws HibernateException {
try {
DatabaseMetaData meta = jdbcConnection.getMetaData();
ResultSet rs = null;
try {
if ( (isQuoted && meta.storesMixedCaseQuotedIdentifiers())) {
rs = meta.getTables(catalog, schema, tableNamePattern, TYPES);
} else if ( (isQuoted && meta.storesUpperCaseQuotedIdentifiers())
|| (!isQuoted && meta.storesUpperCaseIdentifiers() )) {
rs = meta.getTables(
StringHelper.toUpperCase(catalog),
StringHelper.toUpperCase(schema),
StringHelper.toUpperCase(tableNamePattern),
TYPES
);
}
else if ( (isQuoted && meta.storesLowerCaseQuotedIdentifiers())
|| (!isQuoted && meta.storesLowerCaseIdentifiers() )) {
rs = meta.getTables(
StringHelper.toLowerCase( catalog ),
StringHelper.toLowerCase(schema),
StringHelper.toLowerCase(tableNamePattern),
TYPES
);
}
else {
rs = meta.getTables(catalog, schema, tableNamePattern, TYPES);
}
while ( rs.next() ) {
String tableName = rs.getString("TABLE_NAME");
System.out.println("table = " + tableName);
}
}
finally {
if (rs!=null) rs.close();
}
}
catch (SQLException sqlException) {
// TODO
sqlException.printStackTrace();
}
}
public static void main(String[] args) {
Connection jdbcConnection;
try {
jdbcConnection = DriverManager.getConnection("", "", "");
getTableMetadata(jdbcConnection, "tbl%", null, null, false);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
回答4:
If you want to use a high-level API, that hides a lot of the JDBC complexity around database schema metadata, take a look at this article: http://www.devx.com/Java/Article/32443/1954
回答5:
public static ArrayList<String> getTablesList(Connection conn)
throws SQLException {
ArrayList<String> listofTable = new ArrayList<String>();
DatabaseMetaData md = conn.getMetaData();
ResultSet rs = md.getTables(null, null, "%", null);
while (rs.next()) {
if (rs.getString(4).equalsIgnoreCase("TABLE")) {
listofTable.add(rs.getString(3));
}
}
return listofTable;
}
回答6:
@Transactional
@RequestMapping(value = { "/getDatabaseTables" }, method = RequestMethod.GET)
public @ResponseBody String getDatabaseTables() throws Exception{
Connection con = ((SessionImpl) sessionFactory.getCurrentSession()).connection();
DatabaseMetaData md = con.getMetaData();
ResultSet rs = md.getTables(null, null, "%", null);
HashMap<String,List<String>> databaseTables = new HashMap<String,List<String>>();
List<String> tables = new ArrayList<String>();
String db = "";
while (rs.next()) {
tables.add(rs.getString(3));
db = rs.getString(1);
}
List<String> database = new ArrayList<String>();
database.add(db);
databaseTables.put("database", database);
Collections.reverse(tables);
databaseTables.put("tables", tables);
return new ObjectMapper().writeValueAsString(databaseTables);
}
@Transactional
@RequestMapping(value = { "/getTableDetails" }, method = RequestMethod.GET)
public @ResponseBody String getTableDetails(@RequestParam(value="tablename")String tablename) throws Exception{
System.out.println("...tablename......"+tablename);
Connection con = ((SessionImpl) sessionFactory.getCurrentSession()).connection();
Statement st = con.createStatement();
String sql = "select * from "+tablename;
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metaData = rs.getMetaData();
int rowCount = metaData.getColumnCount();
List<HashMap<String,String>> databaseColumns = new ArrayList<HashMap<String,String>>();
HashMap<String,String> columnDetails = new HashMap<String,String>();
for (int i = 0; i < rowCount; i++) {
columnDetails = new HashMap<String,String>();
Method method = com.mysql.jdbc.ResultSetMetaData.class.getDeclaredMethod("getField", int.class);
method.setAccessible(true);
com.mysql.jdbc.Field field = (com.mysql.jdbc.Field) method.invoke(metaData, i+1);
columnDetails.put("columnName", field.getName());//metaData.getColumnName(i + 1));
columnDetails.put("columnType", metaData.getColumnTypeName(i + 1));
columnDetails.put("columnSize", field.getLength()+"");//metaData.getColumnDisplaySize(i + 1)+"");
columnDetails.put("columnColl", field.getCollation());
columnDetails.put("columnNull", ((metaData.isNullable(i + 1)==0)?"NO":"YES"));
if (field.isPrimaryKey()) {
columnDetails.put("columnKEY", "PRI");
} else if(field.isMultipleKey()) {
columnDetails.put("columnKEY", "MUL");
} else if(field.isUniqueKey()) {
columnDetails.put("columnKEY", "UNI");
} else {
columnDetails.put("columnKEY", "");
}
columnDetails.put("columnAINC", (field.isAutoIncrement()?"AUTO_INC":""));
databaseColumns.add(columnDetails);
}
HashMap<String,List<HashMap<String,String>>> tableColumns = new HashMap<String,List<HashMap<String,String>>>();
Collections.reverse(databaseColumns);
tableColumns.put("columns", databaseColumns);
return new ObjectMapper().writeValueAsString(tableColumns);
}
来源：https://stackoverflow.com/questions/2780284/how-to-get-all-table-names-from-a-database