http断点续传简单实现（java)

/* _JpTHpqu  
**SiteFileFetch.java 
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*/ ?aaYka]  
package NetFox; ]S(nA!]  
import java.io.*; MYJDfI  
import java.net.*; hHEn  
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public class SiteFileFetch extends Thread {  CU\r I  
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SiteInfoBean siteInfoBean = null; //文件信息Bean \HoVS  
long[] nStartPos; //开始位置 ~EDO< O>3  
long[] nEndPos; //结束位置 `aMnTF5:  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 9@h-q(-  
long nFileLength; //文件长度 V?MaI.g
j  
boolean bFirst = true; //是否第一次取文件 0^P9)<k'  
boolean bStop = false; //停止标志 A@.ruG$  
File tmpFile; //文件下载的临时信息 ?)qm=mebY  
DataOutputStream output; //输出到文件的输出流 t P'._0n0  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） H5FWk  
public SiteFileFetch(SiteInfoBean bean) throws IOException S2I{?y&K  
{ >r:
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siteInfoBean = bean; o9D#d\G  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); nm|"9|/  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); IQ#Kod;)  
if(tmpFile.exists ()) 5?#AS#TD'  
{ .Pe^u%J6F  
bFirst = false; `sdbo](76  
read_nPos(); U z)G Y  
} U&+lw=  
else FGMYpapc~  
{  #s=\  
nStartPos = new long[bean.getNSplitter()]; wXeJjE%j:3  
nEndPos = new long[bean.getNSplitter()]; =6'D/|
3  
} $xcU*?=K  
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} @`sZV8  
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public void run() KH$o X\v  
{ d$D3iv^hyx  
//获得文件长度 OYfP!,+bn  
//分割文件 ui*CA^ Y
 
//实例FileSplitterFetch Ag]Hk%  
//启动FileSplitterFetch线程 yle~hL  
//等待子线程返回 v Dph}Z  
try{ bsWDjV~  
if(bFirst) n QOLR?%  
{ M)nf(jw#G  
nFileLength = getFileSize(); IrP6Rxh  
if(nFileLength == -1) 44hz,  
{ Z
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System.err.println("File Length is not known!"); V,3$>4x  
} 1B`0.M'd  
else if(nFileLength == -2) O;;vz+ j  
{ ^@q$c  
System.err.println("File is not access!"); V/DdV}n!  
} `ucr;P  
else `{@?O%UB  
{ TSd;L u%hr  
for(int i=0;i<nStartPos.length;i++) !B*d,_9c  
{ :B_ itl0{e  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 'l'[U  
} (B
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for(int i=0;i<nEndPos.length-1;i++) ""F'Nzy  
{ X@7e7  
nEndPos = nStartPos[i+1]; @ GzN0yXhR  
} /I' np  
nEndPos[nEndPos.length-1] = nFileLength;
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} 8:UV;5@  
} _i&awm/U  
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d
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//启动子线程 R$40cW3`  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length];  ^pZ\:  
for(int i=0;i<nStartPos.length;i++) D\GP+Ota  
{ !bD`2m[Q  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ^,Y#_$oR  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), \Mod4tQ  
nStartPos,nEndPos,i); y>m=A41:g  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); XS"lR |  
fileSplitterFetch.start(); 9Lxa?Y1  
} 9k!#5_ M  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), KbF,jm5  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 9/S-=VOe.t  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", U_c9T>=  
nEndPos = " + nFileLength); s@bo df&  
// fileSplitterFetch[nPos.length-1].start(); A&QO]8  
1=%\4\  
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//等待子线程结束 VFwp .1oa!  
//int count = 0; 6tmn1:  
//是否结束while循环 > jvi7  
boolean breakWhile = false; '=vD!6=0@  
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while(!bStop) k@ZmI^  
{ cw{[% 7  
write_nPos(); $q;dsW,8  
Utility.sleep(500); O>`DR0  
breakWhile = true; m-No 8)2yA  
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for(int i=0;i<nStartPos.length;i++) B?J#NFUb  
{ y"SVZ} ;|  
if(!fileSplitterFetch.bDownOver) h"G#} C]  
{ sIh,@
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breakWhile = false; +V6N/{^5  
break; $n?@zd@53  
} LHz-/0[  
} gaw
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if(breakWhile) }@:vq8%Q  
break; _(s|@UT#  
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//count++; Ey
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//if(count>4) k:0HsN!F9  
// siteStop(); *L.+w-g&&  
} BHw/~Hd4  
 Ju#t^P  
H:BWv08~5  
System.err.println("文件下载结束！"); A/EW57v"  
} rOu7r4  
catch(Exception e){e.printStackTrace ();} bytAdS$3  
} SXA_P{j&a  
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/"$;
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//获得文件长度 r4h4A w{  
public long getFileSize() KfsURTZ  
{ ga~C?H,K  
int nFileLength = -1; }?=$?3W  
try{ .* xaI+:  
URL url = new URL(siteInfoBean.getSSiteURL()); -&* 4~  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); OXuBtW*,z+  
httpConnection.setRequestProperty("User-Agent","NetFox"); q8{)27f,  
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int responseCode=httpConnection.getResponseCode(); 2\M^_x$N  
if(responseCode>=400) aoh"<I%]>4  
{ ;|f|d?Q\  
processErrorCode(responseCode); \ueo^p]_?  
return -2; //-2 represent access is error pAo5c4y!4  
} E1'HdOh&z  
j ,'$i[F'  
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String sHeader; |Psi?'4  
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for(int i=1;;i++) Re{vO&.  
{ {]/}3t  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); %(,Kj ~0  
//Utility.log(in.readLine()); ?6F\cl0.  
sHeader=httpConnection.getHeaderFieldKey(i); _>8ZL)NQQ  
if(sHeader!=null) W4Ey]y"  
{ c-L1 Bkw  
if(sHeader.equals("Content-Length")) B6&;nU>;  
{ %EuJ~;x(Mg  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Quy&CV{@  
break; |Fk>NX  
} +wU9d8W  
} xG JX~)  
else dMw0Aw,2]8  
break; F/FUKXxx  
} 0HA`  
}
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catch(IOException e){e.printStackTrace ();} oz(V a!  
catch(Exception e){e.printStackTrace ();} ab5 a>w6}  
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Utility.log(nFileLength); 60B6~@]P  
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return nFileLength; [=[>1<L>  
} 59;p|  
]Z?y\L*M-  
~ [k0ay  
//保存下载信息（文件指针位置） wJs#rkW  
private void write_nPos() nm)H\i  
{ 8X,dVX5LT  
try{ 1&JPyW  
output = new DataOutputStream(new FileOutputStream(tmpFile)); eM";P/XaX  
output.writeInt(nStartPos.length); #)&kF+  
for(int i=0;i<nStartPos.length;i++) mhZ{}~  
{ 9?5'>WO  
// output.writeLong(nPos); &eL02:[  
output.writeLong(fileSplitterFetch.nStartPos); $9!2c/  
output.writeLong(fileSplitterFetch.nEndPos); ^Oy97Y  
} ?/Bp8q(  
output.close(); )N4!zuSVf  
} A}Q6DHh26  
catch(IOException e){e.printStackTrace ();} c]SXcA;Pmv  
catch(Exception e){e.printStackTrace ();} z>rl7&[@  
} v]UT1
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*E*= ;B
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//读取保存的下载信息（文件指针位置） _Mi`]VSq9  
private void read_nPos() x3j)'`=15  
{ J:<mq5[  
try{ eD4D<\*  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ws1io.  
int nCount = input.readInt(); !6Sr*a*5  
nStartPos = new long[nCount]; ;L1Q"Hxh  
nEndPos = new long[nCount]; |$*1!pL-QP  
for(int i=0;i<nStartPos.length;i++) or~2r8  
{ LhN?j5XqM  
nStartPos = input.readLong(); 3q'["SS  
nEndPos = input.readLong(); 0_F6t-  
} b.mcP@  
input.close(); Ass :  
} 6#[  
catch(IOException e){e.printStackTrace ();} ]S@
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catch(Exception e){e.printStackTrace ();} zSy^vM;6zf  
} BvQMq5&  
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private void processErrorCode(int nErrorCode) S$~T8_m^U  
{ 0&M~lJ  
System.err.println("Error Code : " + nErrorCode); =<yMB d\  
} ~s3X&!#   
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//停止文件下载 ;a"g<v  
public void siteStop() Yatd$`,hW  
{ b 6kDkE  
bStop = true; s7(NFX
5  
for(int i=0;i<nStartPos.length;i++) \wMqVRPoQ  
fileSplitterFetch.splitterStop(); j<"@Y7  
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k P]'  
} _}bs0 kIz  
} I+08tXO  
//负责部分文件的抓取 pco:]3BF6  
**FileSplitterFetch.java 5;WESk  
*/ B*0TM+  
package NetFox; Y-yozt  
#mT\B[4h  
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import java.io.*; &>nB@SQZ  
import java.net.*; |ry![\  
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public class FileSplitterFetch extends Thread { )RUx  
` nd/N#  
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String sURL; //File URL eELLnU{"  
long nStartPos; //File Snippet Start Position d-X6yRjnj  
long nEndPos; //File Snippet End Position 4d x4hBd  
int nThreadID; //Thread's ID nXU`^<nA  
boolean bDownOver = false; //Downing is over u[:-^H  
boolean bStop = false; //Stop identical `T'[H/  
FileAccessI fileAccessI = null; //File Access interface t=l@(%O 0_  
_*l+ze[a  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ~ 3!yd0[k  
{ @\*`rl]  
this.sURL = sURL; .ZOG,h+8  
this.nStartPos = nStart; WswM5RN  
this.nEndPos = nEnd; Y0z)5),[U:  
nThreadID = id; 8SZZ_tS3r  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 plNoI1st  
} 8}M-b6RV  
MnLo{G]  
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public void run() ltWEA  
{ 3<XP/c";  
while(nStartPos < nEndPos && !bStop) b6%[?k  
{ vRhI:E)So#  
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try{ m|uVmg!*  
URL url = new URL(sURL); FOyANN'  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wC>}9
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httpConnection.setRequestProperty("User-Agent","NetFox"); 7v']wA r]  
String sProperty = "bytes="+nStartPos+"-"; 7|@FN7]5NF  
httpConnection.setRequestProperty("RANGE",sProperty);
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Utility.log(sProperty); dz6&TdEl  
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InputStream input = httpConnection.getInputStream(); G1 K@Ir<  
//logResponseHead(httpConnection); a S;z YD  
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byte[] b = new byte[1024]; .DR*MQI9  
int nRead; d53Eu`QW?  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) w#d7  
{ A3Xfu$[u  
nStartPos += fileAccessI.write(b,0,nRead); <B Vx%  
//if(nThreadID == 1) :R'={0Jg  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 2^X<n{0N)  
} \b
;z$P\+*  
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Utility.log("Thread " + nThreadID + " is over!"); G_QV'zQ  
bDownOver = true; 6ys|'<?  
//nPos = fileAccessI.write (b,0,nRead); 6vfut$)[{  
} lyS`X  
catch(Exception e){e.printStackTrace ();} Fy*t[>  
} `t7z LC^c  
} K_Pbzj4(P  
csFLBP  
%N#A1   
//打印回应的头信息 7](aPm8  
public void logResponseHead(HttpURLConnection con) :IX_|8e ^  
{ ^\oMsU5(  
for(int i=1;;i++) &
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{ D!DL6l`  
String header=con.getHeaderFieldKey(i); 3o2x&v  
if(header!=null) kmg/hNtN  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); \IhHbcF`d  
Utility.log(header+" : "+con.getHeaderField(header)); (j(hr'f  
else -]Ny-[P  
break; yJ:rry  
} FJp<J  
} 7\AoMk}  
m;J'y2h =$  
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public void splitterStop() ok1w4#%,  
{ \;+TZ1i_  
bStop = true; 0}`0!Kv  
} WR9-HPF  
}vb.>hy  
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} 0Of6$`  
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/* *&z!y/  
**FileAccess.java 7*kTu0m  
*//文件访问(定位，写) 7sU+
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package NetFox; qL?$u07<9'  
import java.io.*; FMtg7+Q|>  
sk5B} -  
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public class FileAccessI implements Serializable{ o?d`o$  
J^=Xy(3e  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 -;O"Y?ME  
RandomAccessFile oSavedFile; \bies1TBB^  
long nPos; tmQ,>  
6st^-L  
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public FileAccessI() throws IOException N[I ?x5:u  
{ GBTwQYF  
this("",0); 9aYVbq""  
} ck$>  
:7*9W|e  
BQ=JZ4&  
public FileAccessI(String sName,long nPos) throws IOException h05BZrE  
{ f.c2AY~5[  
oSavedFile = new RandomAccessFile(sName,"rw"); B@ >t$jK  
this.nPos = nPos; On(.(7sNc  
oSavedFile.seek(nPos); yb-4[C:i  
} @zJiR{Je-U  
`Bb32L  
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public synchronized int write(byte[] b,int nStart,int nLen) @ %o'  
{ wkY$J\J  
int n = -1; `NyO|9/4
 
try{ HOrXxxp1^  
oSavedFile.write(b,nStart,nLen); n0)y|B#  
n = nLen; y,6KU$G  
} }((P)\s
  
catch(IOException e) ~"Su2{"8B  
{ L/)eNZ  
e.printStackTrace (); ] I5&'#%2  
} bduHYs+rq  
hb(H-
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return n; K."W/A!  
} |9[)-C~N7  
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} D|2lBU  
hP_{$c{4:g  
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/* _z\qtl~3  
**SiteInfoBean.java DG,m;vg+  
*/ /Ri-iC >  
package NetFox; 6%V#_]  
6A4{6B  
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public class SiteInfoBean { A~;.9{6J[t  
+E+I.}sOB  
#dFE}!"#`  
private String sSiteURL; //Site's URL yQq|!'MKk  
private String sFilePath; //Saved File's Path qykI[4  
private String sFileName; //Saved File's Name [;#^h/5E  
private int nSplitter; //Count of Splited Downloading File xs?]DJj  
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public SiteInfoBean() 'X
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{//nSplitter的缺省值为5 6&btAwvOHx  
//default value of nSplitter is 5 r@Xh8 r;  
this("","","",5); ;+n25_9  
} S-79
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(\4YBaGd  
/S9n!H:MT  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) &-KQ m20n  
{ {~V_6wY g  
sSiteURL= sURL; X=VaBy4#  
sFilePath = sPath; 4rypT-%^;  
sFileName = sName; u"(2Xer  
this.nSplitter = nSpiltter; zX8{
(  
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;(s.G-9S  
} ~g *`E!2  
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public String getSSiteURL() ^t[br6G  
{ 2\#
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return sSiteURL; xw3A|Aj?r  
} T'7x,8&2|  
R7Ns5s3X  
\r}*<CRr6  
public void setSSiteURL(String value) ;nb>IL  
{ GFZx[*+%%z  
sSiteURL = value; V_9>Z?  
} RohD.`D  
wEEFpn_   
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public String getSFilePath() _2eL3xXha.  
{ _m1WY7
  
return sFilePath; nVk]Qe  
} PU%WpI.w  
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J|b:Zo9<f"  
public void setSFilePath(String value) d-"[-+)
-  
{ #Y>d@  
sFilePath = value; 9z(h8H  
} m A|"  
tHo/Vly6Z  
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public String getSFileName() u_S>`I  
{ "HbrYYRb'  
return sFileName; s`,.&  
} fQ,(,^!;  
<$`udP@  
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public void setSFileName(String value) <~Tfi*^+  
{ 7@i2Mz/eV  
sFileName = value; [oS.B\Vc  
} }u~r.=  
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]I0(_e|z}  
public int getNSplitter() +isaqfy/  
{ ]TKM.[[  
return nSplitter; kN$L8U8f  
} H@8 ;6D  
o#F03  
/J'dG%  
public void setNSplitter(int nCount) A\<WnG>xjP  
{ *!+?%e{;b  
nSplitter = nCount; 0}aw9g  
} +luW=
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} "O{:jfq  
^ P=CoLFa  
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/* z/7"!  
**Utility.java
LQP4#7  
*/ R P6R1iN3  
package NetFox; siGt5RH*  
oN
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g/m%A2M&aH  
public class Utility { ,h$j%->U  
]6EXaf#  
4kQL\Ld#E%  
public Utility() dDla?)F  
{ w~=@+U$f  
t2vo;,^euL  
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} #-u?+Nk/  
S#, E)h/  
//线程睡眠 f<G:}I  
public static void sleep(int nSecond) )haHI)xR  
{ *G0r4Ui$  
try{ -* ;`~5  
Thread.sleep(nSecond); #$9rH 2zd  
} ^!>o5Y)  
catch(Exception e) @uI_4a  
{ v:$Y |mh  
e.printStackTrace (); jP|(y]!  
} \muC_9ke  
} )|@UY(VZ^  
nxh9'"th  
//日志 ur2`.dY>3"  
public static void log(String sMsg) !ZlNPPrq}  
{ &za~=+  
System.err.println(sMsg); ssC5YtF7X  
} tmI2BBv  
goV[C]|  
l~Sn`%PgA  
public static void log(int sMsg) sGD b<  
{ Qf]ACN  
System.err.println(sMsg); SpUcrK;1  
} M0zlB{eH  
} /0H39]y!~  
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,4%'~8'3  
/* nY<hfqof  
**TestMethod.java MM%c  
*/ nfMQ3KP  
package NetFox; 8"g.Z*  
e RjpR?!\  
)v67wn*1A  
public class TestMethod { H A(e  
Lqv5"r7eV  
]n:)W.|`R  
public TestMethod() r:Xui-  
{ ///xx/weblogic60b2_win.exe L?n*b  
try{ i XI:yE;  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5);
$dLPvN  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); >_$DKY>$`  
SiteFileFetch fileFetch = new SiteFileFetch(bean); nn_j"Nu  
fileFetch.start(); #ab=]}2W_g  
} j@b4)t  
catch(Exception e){e.printStackTrace ();} 6"W~%FSJX  
@u2nG:FG  
oA&V,r  
} 6Hn3  
!%?X% @9  
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public static void main(String[] args) -)tu$W*  
{ r='"X#CmV/  
new TestMethod(); dviL5Eaj  
} mu/O\'5  
} ArUGa(;f  
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