Java语言JDBC的实用例子

Alan 四月 19th, 2019 1.服务端语言

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JDBC（Java DataBase Connectivity,java数据库连接）是一种用于执行SQL语句的Java API，可以为多种关系数据库提供统一访问，它由一组用Java语言编写的类和接口组成。JDBC提供了一种基准，据此可以构建更高级的工具和接口，使数据库开发人员能够编写数据库应用程序。

连接数据库
使用的连接类是java.sql包中的DriverManager类，方法名：getConnection()，会返回一个数据库Connection对象，它的代码如下：

Modifier and Type	Method and Description
`boolean`	`add(E e)` Adds the specified element to this set if it is not already present (optional operation).
`boolean`	`addAll(Collection<? extends E> c)` Adds all of the elements in the specified collection to this set if they’re not already present (optional operation).
`void`	`clear()` Removes all of the elements from this set (optional operation).
`boolean`	`contains(Object o)` Returns `true` if this set contains the specified element.
`boolean`	`containsAll(Collection<?> c)` Returns `true` if this set contains all of the elements of the specified collection.
`boolean`	`equals(Object o)` Compares the specified object with this set for equality.
`int`	`hashCode()` Returns the hash code value for this set.
`boolean`	`isEmpty()` Returns `true` if this set contains no elements.
`Iterator<E>`	`iterator()` Returns an iterator over the elements in this set.
`boolean`	`remove(Object o)` Removes the specified element from this set if it is present (optional operation).
`boolean`	`removeAll(Collection<?> c)` Removes from this set all of its elements that are contained in the specified collection (optional operation).
`boolean`	`retainAll(Collection<?> c)` Retains only the elements in this set that are contained in the specified collection (optional operation).
`int`	`size()` Returns the number of elements in this set (its cardinality).
`default Spliterator<E>`	`spliterator()` Creates a `Spliterator` over the elements in this set.
`Object[]`	`toArray()` Returns an array containing all of the elements in this set.
`<T> T[]`	`toArray(T[] a)` Returns an array containing all of the elements in this set; the runtime type of the returned array is that of the specified array.

Modifier and Type	Method and Description
`boolean`	`add(E e)` Appends the specified element to the end of this list (optional operation).
`void`	`add(int index, E element)` Inserts the specified element at the specified position in this list (optional operation).
`boolean`	`addAll(Collection<? extends E> c)` Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection’s iterator (optional operation).
`boolean`	`addAll(int index, Collection<? extends E> c)` Inserts all of the elements in the specified collection into this list at the specified position (optional operation).
`void`	`clear()` Removes all of the elements from this list (optional operation).
`boolean`	`contains(Object o)` Returns `true` if this list contains the specified element.
`boolean`	`containsAll(Collection<?> c)` Returns `true` if this list contains all of the elements of the specified collection.
`boolean`	`equals(Object o)` Compares the specified object with this list for equality.
`E`	`get(int index)` Returns the element at the specified position in this list.
`int`	`hashCode()` Returns the hash code value for this list.
`int`	`indexOf(Object o)` Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
`boolean`	`isEmpty()` Returns `true` if this list contains no elements.
`Iterator<E>`	`iterator()` Returns an iterator over the elements in this list in proper sequence.
`int`	`lastIndexOf(Object o)` Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
`ListIterator<E>`	`listIterator()` Returns a list iterator over the elements in this list (in proper sequence).
`ListIterator<E>`	`listIterator(int index)` Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.
`E`	`remove(int index)` Removes the element at the specified position in this list (optional operation).
`boolean`	`remove(Object o)` Removes the first occurrence of the specified element from this list, if it is present (optional operation).
`boolean`	`removeAll(Collection<?> c)` Removes from this list all of its elements that are contained in the specified collection (optional operation).
`default void`	`replaceAll(UnaryOperator<E> operator)` Replaces each element of this list with the result of applying the operator to that element.
`boolean`	`retainAll(Collection<?> c)` Retains only the elements in this list that are contained in the specified collection (optional operation).
`E`	`set(int index, E element)` Replaces the element at the specified position in this list with the specified element (optional operation).
`int`	`size()` Returns the number of elements in this list.
`default void`	`sort(Comparator<? super E> c)` Sorts this list according to the order induced by the specified `Comparator`.
`default Spliterator<E>`	`spliterator()` Creates a `Spliterator` over the elements in this list.
`List<E>`	`subList(int fromIndex, int toIndex)` Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive.
`Object[]`	`toArray()` Returns an array containing all of the elements in this list in proper sequence (from first to last element).
`<T> T[]`	`toArray(T[] a)` Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.

Modifier and Type	Method and Description
`void`	`clear()` Removes all of the mappings from this map (optional operation).
`default V`	`compute(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)` Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping).
`default V`	`computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction)` If the specified key is not already associated with a value (or is mapped to `null`), attempts to compute its value using the given mapping function and enters it into this map unless `null`.
`default V`	`computeIfPresent(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)` If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.
`boolean`	`containsKey(Object key)` Returns `true` if this map contains a mapping for the specified key.
`boolean`	`containsValue(Object value)` Returns `true` if this map maps one or more keys to the specified value.
`Set<Map.Entry<K,V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`boolean`	`equals(Object o)` Compares the specified object with this map for equality.
`default void`	`forEach(BiConsumer<? super K,? super V> action)` Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.
`V`	`get(Object key)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key.
`default V`	`getOrDefault(Object key, V defaultValue)` Returns the value to which the specified key is mapped, or `defaultValue` if this map contains no mapping for the key.
`int`	`hashCode()` Returns the hash code value for this map.
`boolean`	`isEmpty()` Returns `true` if this map contains no key-value mappings.
`Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map.
`default V`	`merge(K key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction)` If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.
`V`	`put(K key, V value)` Associates the specified value with the specified key in this map (optional operation).
`void`	`putAll(Map<? extends K,? extends V> m)` Copies all of the mappings from the specified map to this map (optional operation).
`default V`	`putIfAbsent(K key, V value)` If the specified key is not already associated with a value (or is mapped to `null`) associates it with the given value and returns `null`, else returns the current value.
`V`	`remove(Object key)` Removes the mapping for a key from this map if it is present (optional operation).
`default boolean`	`remove(Object key, Object value)` Removes the entry for the specified key only if it is currently mapped to the specified value.
`default V`	`replace(K key, V value)` Replaces the entry for the specified key only if it is currently mapped to some value.
`default boolean`	`replace(K key, V oldValue, V newValue)` Replaces the entry for the specified key only if currently mapped to the specified value.
`default void`	`replaceAll(BiFunction<? super K,? super V,? extends V> function)` Replaces each entry’s value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
`int`	`size()` Returns the number of key-value mappings in this map.
`Collection<V>`	`values()` Returns a `Collection` view of the values contained in this map.

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