读取Hive中表的结构。本文中包含Table类，Field类用于封装表结构，粗略瞅一遍就ok等
(代码格式注意修改)
1. Table类
public class Table {
private String tableName;
private List<Field> field;
public Table() {
}
public Table(String tableName, List<Field> field) {
this.tableName = tableName;
this.field = field;
}
public String getTableName() {
return tableName;
}
public void setTableName(String tableName) {
this.tableName = tableName;
}
public List<Field> getField() {
return field;
}
public void setField(List<Field> field) {
this.field = field;
}
@Override
public String toString() {
return "Table{" + "tableName=" + tableName + ", field=" + field + '}';
}
}
2. Field类
public class Field {
private String columnName;
private String typeName;
private int columnSize;
private int decimal_digits;
private int nullable;
public Field() {
}
public Field(String columnName, String typeName, int columnSize, int decimal_digits, int nullable) {
this.columnName = columnName;
this.typeName = typeName;
this.columnSize = columnSize;
this.decimal_digits = decimal_digits;
this.nullable = nullable;
}
public String getColumnName() {
return columnName;
}
public void setColumnName(String columnName) {
this.columnName = columnName;
}
public String getTypeName() {
return typeName;
}
public void setTypeName(String typeName) {
this.typeName = typeName;
}
public int getColumnSize() {
return columnSize;
}
public void setColumnSize(int columnSize) {
this.columnSize = columnSize;
}
public int getDecimal_digits() {
return decimal_digits;
}
public void setDecimal_digits(int decimal_digits) {
this.decimal_digits = decimal_digits;
}
public int getNullable() {
return nullable;
}
public void setNullable(int nullable) {
this.nullable = nullable;
}
@Override
public String toString() {
return "Field{" + "columnName=" + columnName + ", typeName=" + typeName + ", columnSize=" + columnSize + ", decimal_digits=" + decimal_digits + ", nullable=" + nullable + '}';
}
}
3. 主要方法
public List<Table> export() {
String showtablesSQL = "show tables";
List<Table> tableList = new ArrayList<Table>();
List<String> tableNameList = new ArrayList<String>();
Connection conn = HiveUtil.getConnection();
Statement stmt = null;
ResultSet tableRs = null; // 存库元数据
ResultSet colRs = null;//存储表元数据
try {
stmt = conn.createStatement();
stmt.executeQuery("use database");
//获取表名
tableRs = stmt.executeQuery(showtablesSQL);
while (tableRs.next()) {
String table = tableRs.getString(1);
tableNameList.add(table);
}
//获取表结构
Field field = null;
Table table = null;
for (int i = 0; i < tableNameList.size(); i++) {
String descTableSQL = "describe ";
List<Field> fieldList = new ArrayList<Field>();
descTableSQL = descTableSQL + tableNameList.get(i).trim();//拼接sql
colRs = stmt.executeQuery(descTableSQL);
while (colRs.next()) {
field = new Field();
field.setColumnName(colRs.getString(1));
field.setTypeName(colRs.getString(2));//测试大小
fieldList.add(field);
}
table = new Table();
table.setTableName(tableNameList.get(i).trim());
table.setField(fieldList);
tableList.add(table);
}
} catch (SQLException ex) {
Logger.getLogger(ExportOracleTable.class.getName()).log(Level.SEVERE, null, ex);
} finally {
if (colRs != null) {
try {
colRs.close();
} catch (SQLException ex) {
Logger.getLogger(ExportOracleTable.class.getName()).log(Level.SEVERE, null, ex);
}
}
if (tableRs != null) {
try {
tableRs.close();
} catch (SQLException ex) {
Logger.getLogger(ExportOracleTable.class.getName()).log(Level.SEVERE, null, ex);
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException ex) {
Logger.getLogger(ExportOracleTable.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
return tableList;
}
4. 在新库中建表
public void createTableToHive(List<Table> list) {
Connection conn = HiveUtil.getTargetConnection();
Statement stmt = null;
try {
for (Table table : list) {
StringBuffer sql = new StringBuffer();
StringBuffer schemaSQL = new StringBuffer();
StringBuffer indexSQL = new StringBuffer();
sql.append("create table if not exists ");
sql.append(table.getTableName());//create table test
for (int i = 0; i < table.getField().size(); i++) {
sql.append(" (" + table.getField().get(i).getColumnName() + " " + table.getField().get(i).getTypeName());//create table test (name varchar(2), age int)
// if (table.getField().get(i).getColumnSize() == 0) {//条件需要测试
// sql.append("(" + table.getField().get(i).getColumnSize() + ")");
// }
if (i == table.getField().size() - 1) {
continue;
}
sql.append(",");
}
//执行
stmt = conn.createStatement();
stmt.executeQuery("use database");
stmt.executeQuery(sql.toString().trim());
// stmt.executeQuery(schemaSQL );
}
conn.commit();
} catch (SQLException ex) {
Logger.getLogger(CreateHiveTable.class.getName()).log(Level.SEVERE, null, ex);
} finally {
if(stmt != null) {
try {
stmt.close();
} catch (SQLException ex) {
Logger.getLogger(CreateHiveTable.class.getName()).log(Level.SEVERE, null, ex);
}
}
if(conn != null) {
try {
conn.close();
} catch (SQLException ex) {
Logger.getLogger(CreateHiveTable.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}